Toilet training

My son is 2.5 he has been toilet training for 2 weeks after 3 days he had pretty much cracked it he wouldn't tell us but when we took him he would go and he wouldn't have any accidents. Then 4 days ago he started saying "all done" before he even sat down every time I took him and would end up having an accident. He is now having 2-3 a day. I do not want to put him back in nappies as that's just confusing for him. I have tried bribery with chocolate but it's not working.

Any advice?