Step 1: Preparation
Determine a week that you have more time. (We picked the 4-day Easter weekend as there was no free week coming up)
Prepare your child mentally (When it gets warm outside, you won't wear diapers anymore...).
Welcome them in the bathroom when you are going. (We didn't focus on this step, I think it happened naturally due to the layout of our house)
Go potty shopping together (avoid Cars 3-in-one!) and read potty books (Our favourite is
Potty by Leslie Patricelli; we also like
The Potty Book for Boys
Step 2: Go For It!
First week-end, have your child go on the toilet every half hour. They have to try. This is to determine their schedule. (At first our guys sometimes needed "incentives" just to sit - but once they sat, they went) Keep notes.
(Here are our notes:
Day 1 #1: Both boys went every half hour. One accident each.
Day 1 #2: Vanh went 7 times. Max didn't go at all.
Day 2 #1: Both boys went every hour. Max had one accident.
Day 2 #2: Neither boy went until after going to bed for the night (in their diapers).
Day 3 #1: Vanh went every 90 minutes. Max went every 2 hours. Can't remember who, maybe both had one accident?
Day 3 #2: Vanh went once. Max didn't go.
Day 4 #1: Both on an every 2 hour schedule. Vanh had one accident but we decided to move on to the next step (undie shopping) anyway...
Day 4 #2: Nothing again until well after bedtime diapers, at which point it was obvious there should have been a couple earlier.)
Step 3: You're A Big Boy Now.
When no accidents, go with your child to buy big boy underpants. Let them pick. (Note: Thomas size 2s are significantly larger than Cars size 2s. Also: Don't shop in any underwear aisles with carpets, just in case your child gets so overwhelmed with excitement he pees. Oh, and pull-ups don't always work for some reason, in fact they can leak enough to leave footprints on carpet if your child takes off his pee-covered flip-flops...)
Ongoing: When there is an accident, just tell your child that you know he/she can do it. When there is success, congratulate and make it a big deal (we used lots of praise and excitement, intermittent chocolate chips, a few toy motorcycles, and choice of video as rewards). Avoid food treats (especially if you pick Easter weekend when your kids are going to be eating chocolate and candy for all three meals already)
You can use pull-ups or diapers. You can even slip the underpants over the diaper to encourage them. You can also put the diaper over the undies if you are pretty sure they can do it but are going somewhere you can't afford an accident. (We didn't use any diapers unless we were going out. It didn't seem to influence the boys success rate whether they were wearing diapers or not. We collected a bunch of old cotton pajama bottoms for that first weekend - you can see some in the photos.)
This method is adapted from a friend of a friend, her blog is private so I won't say her name but thank you so much for sharing, seems to be going well so far! Hope this helps someone else as much as it helped us.
(PS I know I said I wasn't going to write any more until we were done but that was before I spent 4 days straight in the bathroom and ended up with nothing else to write about)