Is it possible to create a formula with If/Then using days?

Example, I want to create a workbook with an entire month. I want to be able
to use this every month but only change the first date of the month. However,
if the date is a Sunday, I want it to add 2(two) days and skip Sunday.
EXAMPLE: If Day= Sunday, then add 2 days, otherwise add only one day. (IF
a3=SUN, then B1+2, B1+1)

I hope this makes sense. Does anyone know a formula for this? Thanks.