We are about to embark on the same thing I have a 3 1/2 year old and a 8 month old and we are getting a puppy in a couple of weeks.
I have tried to be as organised as possible. I have a crate, a puppy pen, plenty of puppy toys and am willing and able to supervise all interaction. I know I am in for a lot of work but I am really looking forward to it.