toilet training

Our son is almost 2.5 and was taking off his nappy, wanting to use toilet etc.
so a week ago we put him in jocks and it started off well. All wee and pop in the toilet. He gets himself up on the seat, all good. Refuses to use a potty, no probs.
Fast forward to say 5 & 6 he always takes his pants off (it's virtually impossible to keep him in clothes) and then wee's and poos around the house! He'll then pick his poo up like its a special surprise and take it to the toilet. He will wee on anything.
Suffice to say it's driving us insane.
He speaks very well, he knows when he needs to go.
We'll put him on the toilet, he'll 50% of the time go, but if he doesn't do anything, he will literally 3 mins later on the carpet.
SO tempted to put him back in pull ups! He's our 3rd so we know what we're doing but he's (I think) just very cheeky about it! Our other 2 sons we toilet trained when they said no more nappies at almost 3. Maybe it's just a little bit too soon?
We don't smack or punish or shame but we're quietly getting really frustrated and annoyed!
Please any words of wisdom.
Thank you ?