My eldest son was 23 months old when my youngest was born... and I wish we had tried harder to train him then. He was ready, but I had read that you shouldn't train when a new child was expected.... etc. So I didn't really do it. Sigh.
When we tried to train a few months after his brother was born, he was no longer at a good potty training point... totally reisistant. BUT... he did become ready at about 29 months again... so off I went with "Potty Training in One Day".
It worked! The book was written in the 70s.... and as such, there are some slight modifications that most Moms/Dads make... but it works (and is based on research.)
Anyways... first off... assemble the supplies...
* cloth training pants
* doll and a potty (author recommends using a doll that wets, but many Moms use a favorite doll/stuffed animal and then improvise going potty with a syringe of water)
* potty (I like the Graco Training Rewards one.... cushy seat... big, easy to empty potty, converts to a step stool/potty topper (with handles on the side))
* rewards (this is where I differed from the book... book recommends orange soda, sweets, etc... while we had some of those (no soda though), used other things as well....stickers, grapes, apples, Baked Lays, etc.)
BIG IDEA is... you praise/reward for dry pants... not for using the potty
Give lots of drinks.... and take to potty every 15 minutes at first.
Teach your child to remove pants, training pants, etc. So that you don't have to do it every time.
Keep asking... "Is your underwear dry??" And have the child check... if so.... s/he gets either verbal praise or a treat.
Push fluids!! (More opportunities) For us, not an issue... my son drinks like a fish
Don't ask.... do you want to go potty...at first, as most kids will say "no." Just take him/her to the potty.
Anyways, we started at 9 a.m. By 2 p.m., he basically had it down. Stayed dry at night as well. Had a few accidents here and there (mainly not making it to the potty in time... or partial accidents(started to pee, and then went to the potty), but not a whole lot. Easiest thing I ever did.
Book is on Amazon for like $6.00