Anxious/advice?

So my daughter is almost 11 months old and I really think I’ve settled on trying to conceive number two at the end of this summer. When should I go off my birth control pill if I wanted to ideally conceive in late August or September? I’m also really thinking about buying preseed since my ph is always wonky when ttc and since it took a little longer than expected for number one.

Any advice would be awesome and I know i might be jumping the gun just a little bit I want all the information i can get! TIA!