How do you book when your 7/11 month day doesn't exist?

[MommyMK]

I just booked a stay starting on 9/30/16 and I want to change to a different resort at the 7 month mark, but 7 months before September 30th is February 30th, which obviously doesn't exist. When do I book then? February 28th? March 2nd? Help please.

 

[erionm]

March 1st.

 

[OKW Lover]

If the 7 or 11 month window falls on a nonexistent date, the earliest you can book is the next day.