it's hard to say because it's random. also, have you been taking to your smug villager a lot? it seems to help if you have a higher friendship rating with them.
You can't force a villager to request a PWP. It's completely random. Sometimes I get requests several days in a row and other times, it'll be weeks before I get one.
It's anytime really. There's no set time for any personality to give you a PWP. Personally I've had almost all the jock ones and all the ones that can be suggested by anyone. Only had one cranky and zero smug or uchi.
Just keep doing the diving trick. Maybe dig holes around your smug villager too so they stay in that one place, every time you come out the water, go right up to them. It might not always work though, it's always more difficult to get PWPs when you're just trying to get them from one villager
trap the villager (dig holes all around them) and then do the diving trick / stay out of their sight for around 5-10 minutes. go back to the villager and walk in front of them, if they don't ping talk to them and repeat. if they start saying that you've been playing for too long and should rest just save and quit and reopen the game.
this might take a while so idk just have patience i guess.... i only need uchi, peppy and cranky pwps so i always trap the villagers of these personalities so i have more villagers that might ping about a pwp ;;
once you've gotten one pwp ping you should stop for the day, getting more pwp suggestions than once a day is really rare (if not impossible)