I would use a variation on eduzs code and make use of styles which typically have the bold and keep with next settings
Code:
Sub test()
Dim MyPara As Paragraph
For Each MyPara In ActiveDocument.Paragraphs
Select Case Trim(MyPara.Range.Words.First)
Case "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"
MyPara.Style = "Heading 1"
End Select
Next
End Sub