I knew I wanted another one after #1 but it wasn't til he was about 15mo that I really started thinking right I'm clucky lol then it took us 6 months to actually decide to start TTC coz I'd had awful PND and we wanted to make sure I was on top of things before I went back into the hormonally disturbed world of baby breeding. We got a BFP the first month we went for it and theres 2y6m19d between the boys lol its a great gap but we plan on having a slightly smaller one next time round.
I think since I haven't had any probs with PND this time round we'll start TTC as soon as I get that clucky, I know I'm ready feeling which I'm expecting to kick in fairly soon after #2s first bday. We're planning to TTC in April/March but if I'm not feeling ready then its a flexible date
IMO the gaps between kids don't really matter. I know siblings who were born super-close together, siblings born super-far apart and siblings with a 2yr-ish age gap and ultimately the way they each feel about it (different families, etc BTW) comes down to how they were parented, not the gap.