When did you have your second baby?

How long did you wait before you had your second baby?  I am a crazy schedule maker and I like to sort things out in my mind for me to have focus and direction.  My sister and I are 20 months apart and fight like cats and dogs, my baby just turned 1 and I was now thinking when should I have the second to sort of prevent sibling rivalry as much as possible plus give me a breather to re-organize.  I was now thinking of waiting until she was like a year and a half and until I lost some weight.  We are financially stable and we have more than enough babysitters but we have our marital rocky moments too.  I just dont know what to do.  Come on ladies, give me some advice about what worked for you in when you had your kids!

I want to not have anymore after I turn 35 and I am turning 31 this coming year and think I will stop having kids at 3.  Wait until May, will have by Feb-March, then turn 32, wait another year or so, then may have last one by 34.