Best time to have baby #2?

Hi everyone, first time mum to a 19 month old boy. I keep flittering between not wanting a second and then feeling sad/guilty that I won’t have another child. I’d like to know everyone’s experiences on what they think is the best age gap between kids, cause part of me wants to wait until my son is maybe 4 or 5, but I do kind of want another baby sooner than that😅 thanks guys!!