I agree with what everyone else has been saying. My children are all 2 years apart. I've had a little bit different situation with them because my last two were 7 and 6 weeks early and spent 3 weeks in the NICU. Once we got the new baby home, the best thing was to have the other sibling(s) involved in as much as possible. With my 3rd, I've bottle fed from the beginning, so I let them help me hold the bottle, put the bottle in the sink after he's done, get the diaper & wipes, throw the dirty diaper in the trash, etc. Having them help out makes them feel good about being the "big sister." Another thing, is when they ask to hold their brother, I let them.
Potty training-we were in the process of training with our 1st when our 2nd was born and she reverted back for a little while but was ready to be completely trained a few months later. We haven't started our 2 year old yet but we'll start by the end of this month. I just didn't want to deal with the reverting back! :)
Another thing that will be nice with having their birthdays so close together will be you'll be able to do one big birthday party for them for a while. My two girls were both born in July (2 years & 6 days apart) so we can still get by with one party since all their friends are the same right now! :)
Congratulations on your 3rd!