Welcome to the board, April1976!
Has your 5 yo son been to the doctor to make certain there is not a health issue?
Consistancy on your part is very important.
Get him into a daily routine.
Potty him every 1 hour or 2 hours.
Get up - go to the toilet.
Eat breakfast - go to the toilet.
Play time - go to the toilet.
Before lunch - go to the toilet.
After lunch - go to the toilet.
Play time - go to the toilet.
Snack time - go to the toilet.
TV time - go to the toilet.
Before supper - go to the toilet.
After supper - go to the toilet.
Bath time - go to the toilet.
Story time - go to the toilet.
Bedtime - go to the toilet.
Get him up in the middle of the night - go to the toilet.
Every time he goes do the stickers or other positive reinforcement.
Remind him that to go to school, he needs to go to the toilet.
Are there other adults that can reinforce potty training?
For a boy, sometimes, it is helpful for a man to help.
Dry out the toilet bowl. Paint a red dot with fingernail polish....makes a good place to aim.
A habit takes 3 weeks/21 days to form.
Let us know how things go.