Always remember, potty training is just like learning any other skill, like walking, riding a bike, or cutting with scissors. It's a process that takes time, and practice, practice, practice!
Here are some suggestions that may, or may not work for your child. You know them best. Pick and choose what works for you, and try new things that you feel will work well for your child.
Have child potty 2-3 times a day at roughly the same time. Upon waking up, before nap, before bath time. Choose times that work for you but be consistent. This will make it a routine that children can expect.
The process matters, not just the product. Have the child sit for a maximum of one (yes ONE) minute. Sing a short song, count to five or ten, or count down and say "blast off!" This should be an unemotional time. If something happens, great! Praise, high fives, whatever works. If nothing happens, that's fine, too. Practice wiping (if appropriate), flushing, washing. Use words, like "I see that you tried," or "You tried to go pee pee in the potty."
Let your child help pick out new underwear at the store. If they'd like, let them wear it over their diaper or pull up. Let them choose the underwear they want to wear for that day. Anything that includes them in the process.
When out and about - take them to the restroom. Talk about triangles for Women's Room, rectangles for Men's. What kind of sink do they have? The color of the walls? Is the soap/water/towels automatic? Anything that is interesting. Remember, this will all make the process more interesting and more appealing. Even if you don't need to, check out the rest rooms and go through the motions.
When you feel that your child is showing readiness signs...staying dry for several hours, dry after nap overnight, showing an interest in the potty make a plan. Pick a time when you will be home consistently for at least 4 full days (over Thanksgiving, winter break or Pesach so you can master the basics at home before traveling out to new potties).
At home, take them potty every 20-30 minutes. Give them a warning that in 2-5 minutes it'll be time to try. If they are involved in a game, use that as a tool. "When you finish that building, we'll try to potty." Remember, "TRY" is the most important word - it's not a failure if they don't produce.
Be consistent once you begin. And always remember, it will take time. For some it'll be a week or two, for others it could be a month, or longer. They will get there - promise! Let them know diapers are all gone except for the night time diaper/nap diaper (show them it is thicker and say bye -bye to day time diapers).
Bring the tiny potty chair into the living room, outside when playing, and in back of car when going to the park. Accessibility is really important in the first few weeks. This makes it easy to stop what you are doing and go potty. Especially when playing in the living room watching TV and playing. Gradually moved the potty further away until it was in the bathroom.
Let us know if there is anything we can do to assist in the process. We'll be happy to take the children potty more frequently in the class. Please remember that we want to make this a successful experience for the child at school. We will not insist that they try if they are resistant.