Rolling 30 days... Different rows

Hi,

Im trying to set up a rolling 30 day variance tracker. I want my months set up in there own row.

I used the formula =SUMIF($B$3:B3,">" &B3-30,$B$4:B4) for the first row. Is there a way to continue this in different row.

I'll attach the begining of my work book.

Cheers,