Extract GetFirstDateToRender in the calendar model so it can be executed even before the calendar ViewModels are loaded

Controls/Input/Input.UWP/Calendar/Model/CalendarCenturyViewModel.cs

@@ -25,7 +25,7 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
 
         internal override DateTime GetFirstDateToRender(DateTime date)
         {
-            return CalendarMathHelper.GetFirstDateOfCentury(date);
+            return this.Calendar.GetFirstDateToRenderForDisplayMode(date, CalendarDisplayMode.CenturyView);
         }
 
         internal override DateTime GetNextDateToRender(DateTime date)

Controls/Input/Input.UWP/Calendar/Model/CalendarDecadeViewModel.cs

@@ -25,7 +25,7 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
 
         internal override DateTime GetFirstDateToRender(DateTime date)
         {
-            return CalendarMathHelper.GetFirstDateOfDecade(date);
+            return this.Calendar.GetFirstDateToRenderForDisplayMode(date, CalendarDisplayMode.DecadeView);
         }
 
         internal override DateTime GetNextDateToRender(DateTime date)

Controls/Input/Input.UWP/Calendar/Model/CalendarModel.cs

@@ -418,6 +418,59 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
             return this.View.MeasureContent(owner, content);
         }
 
+        internal DateTime GetFirstDateToRenderForDisplayMode(DateTime date, CalendarDisplayMode displayMode)
+        {
+            DateTime firstDateToRender = date;
+
+            if (displayMode == CalendarDisplayMode.MultiDayView)
+            {
+                DayOfWeek firstDayOfWeek = this.GetFirstDayOfWeek();
+                DateTime firstDateOfCurrentWeek = CalendarMathHelper.GetFirstDayOfCurrentWeek(date, firstDayOfWeek);
+
+                if (!(firstDateOfCurrentWeek.Date <= date.Date && firstDateOfCurrentWeek.AddDays(7).Date >= date.Date))
+                {
+                    firstDateToRender = firstDateOfCurrentWeek;
+                }
+
+                if (!this.multiDayViewSettings.WeekendsVisible)
+                {
+                    firstDateToRender = CalendarMathHelper.AddBusinessDays(date, -this.multiDayViewSettings.VisibleDays);
+                }
+                else
+                {
+                    firstDateToRender = date.AddDays(-this.multiDayViewSettings.VisibleDays);
+                }
+            }
+            else if (displayMode == CalendarDisplayMode.MonthView)
+            {
+                DayOfWeek firstDayOfWeekToUse = this.GetFirstDayOfWeek();
+
+                DateTime monthStartDate = CalendarMathHelper.GetFirstDateOfMonth(date);
+
+                int daysToSubtract = (int) monthStartDate.DayOfWeek - (int) firstDayOfWeekToUse;
+                if (daysToSubtract <= 0)
+                {
+                    daysToSubtract += 7;
+                }
+
+                firstDateToRender = monthStartDate.Date == DateTime.MinValue.Date ? monthStartDate : monthStartDate.AddDays(-daysToSubtract);
+            }
+            else if (displayMode == CalendarDisplayMode.YearView)
+            {
+                firstDateToRender = CalendarMathHelper.GetFirstDateOfYear(date);
+            }
+            else if (displayMode == CalendarDisplayMode.DecadeView)
+            {
+                firstDateToRender = CalendarMathHelper.GetFirstDateOfDecade(date);
+            }
+            else if (displayMode == CalendarDisplayMode.CenturyView)
+            {
+                firstDateToRender =  CalendarMathHelper.GetFirstDateOfCentury(date);
+            }
+
+            return firstDateToRender;
+        }
+
         private void UpdateCurrentView()
         {
             switch (this.DisplayMode)

Controls/Input/Input.UWP/Calendar/Model/CalendarMonthViewModel.cs

@@ -41,17 +41,7 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
 
         internal override DateTime GetFirstDateToRender(DateTime date)
         {
-            DayOfWeek firstDayOfWeekToUse = this.Calendar.GetFirstDayOfWeek();
-
-            DateTime monthStartDate = CalendarMathHelper.GetFirstDateOfMonth(date);
-
-            int daysToSubtract = (int)monthStartDate.DayOfWeek - (int)firstDayOfWeekToUse;
-            if (daysToSubtract <= 0)
-            {
-                daysToSubtract += 7;
-            }
-
-            return monthStartDate.Date == DateTime.MinValue.Date ? monthStartDate : monthStartDate.AddDays(-daysToSubtract);
+            return this.Calendar.GetFirstDateToRenderForDisplayMode(date, CalendarDisplayMode.MonthView);
         }
 
         internal override DateTime GetNextDateToRender(DateTime dateToRender)

Controls/Input/Input.UWP/Calendar/Model/CalendarMultiDayViewModel.cs

@@ -66,24 +66,7 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
 
         internal override DateTime GetFirstDateToRender(DateTime date)
         {
-            DayOfWeek firstDayOfWeek = this.Calendar.GetFirstDayOfWeek();
-            DateTime firstDateOfCurrentWeek = CalendarMathHelper.GetFirstDayOfCurrentWeek(date, firstDayOfWeek);
-
-            if (!(firstDateOfCurrentWeek.Date <= date.Date && firstDateOfCurrentWeek.AddDays(7).Date >= date.Date))
-            {
-                date = firstDateOfCurrentWeek;
-            }
-
-            if (!this.Calendar.multiDayViewSettings.WeekendsVisible)
-            {
-                date = CalendarMathHelper.AddBusinessDays(date, -this.BufferItemsCount);
-            }
-            else
-            {
-                date = date.AddDays(-this.BufferItemsCount);
-            }
-
-            return date;
+            return this.Calendar.GetFirstDateToRenderForDisplayMode(date, CalendarDisplayMode.MultiDayView);
         }
 
         internal override DateTime GetNextDateToRender(DateTime date)

Controls/Input/Input.UWP/Calendar/Model/CalendarYearViewModel.cs

@@ -24,8 +24,8 @@ namespace Telerik.UI.Xaml.Controls.Input.Calendar
         }
 
         internal override DateTime GetFirstDateToRender(DateTime date)
-        {
-            return CalendarMathHelper.GetFirstDateOfYear(date);
+        {
+            return this.Calendar.GetFirstDateToRenderForDisplayMode(date, CalendarDisplayMode.YearView);
         }
 
         internal override DateTime GetNextDateToRender(DateTime date)