DS1 and DS2 are 21 months apart. Wasn't too bad but there was when they were young, a LOT of double teaming so it could spell trouble. There is always a leader and a follower and the follower will always be blamed. :/
This time, DS3 is 8.5 months and I am due with lucky #4 (last baby) so are looking about 17 months. I'm hoping DS3 and his younger sibling will be closer than the first 2 and have more respect for each other but at the same time, I expect a repeat of double teaming.
I will however, be buying a new infant seat (the last one I hated with a passion I gave it away), another cot as DS3 will be staying in his, bottles, binkies, bedding. But I had DS3 bedding designed so I will do the same thing this time. Not too sure as of yet if I am going to replace my buggy with a double or just buy the secondary seat to sit under. However, I can't recline the buggy if I do that so a newborn would have to go underneath and I just don't know how I feel about that.