It really is up to you and your husband as to when is a good time to have another, and even then, it doesn't always work out as you plan, but I do believe it works out for the best no matter what. I wanted my kids to be 2.5 years apart but it took a few months (around 5-6) to get pregnant with my first, so we started trying for #2 when she was 13 months, and it happened on the second try when she was 14 months. My girls are now just under 2 years apart. My oldest will be 5 in two weeks and my little one just turned 3. There are pros and cons to this... I have NO regrets of course, but sometimes I wish it HAD taken longer for my second so I could have enjoyed my oldest's toddlerhood more. It is a blur, between being pregnant then having our second be colicky and fussy as a baby. I forgot my oldest daughter's whole second year of life, I think! I also feel like I am such a better parent now, that I wish my youngest was 2 and not 3.... it is just going way too fast. That could be one reason we want to have a third, god willing!
The pros are that you get through that diaper haze all at once, my kids are literally the best playmates and have the same interests, right down to TV shows and music. Some people mistake them for twins sometimes! I was also able to use all my oldest child's hand me downs since the styles had not changed much and they are both girls. Things were fresh in my mind and I handled the newborn phase pretty well.
One thing I have learned is that my kids actually seem to get busier now and require more work than when they were babies and toddlers, actually. It is hard sometimes when my little one won't nap and my oldest is needy and wants me to spend a ton of time with her... I can't get a lot done on days like that. But I know how fast it goes so I try to keep that in mind when I'm frustrated. Good luck with your decision, I say go for it when you feel ready (though we are only ever so ready!).