when to delay cbet OTT in 3BP

You can abuse the SB vs BTN dynamic on Ignition a little more aggressively as you get more comfortable (I play this pool also). They are not going to adjust/catch on to what you are doing. You range seems fine to me if that is what you are comfortable with.

I play a simplified strategy where I c bet most, if not all of my range OOP in 3b pots for around 1/3 pot. You have a massive range advantage here with overpairs, top pairs, top set and all of the nutted FD's. If you were to draw the line at checking KJss and KJcc and betting only KJhh and KJdd, that would be fine too.

As played, stabbing turn seems better to me than check/calling on a 3 flush coordinated board.

I would include this hand in my flop cbet-check/fold OTT line. Going mix between range check and 1/3 OTF is a very strong strategy. I would consider overbetting hands like A6s or T9s (specially with no flushdraw), sometimes AK, AJ with a heart.
Turn is a check as played imo. I would only bet made hands, but mostly check.
I would stab on non-heart cards more often.

Thanks for your advice guys.
Do you also bet 1/3 with sets and overpairs here then? The board is wet and we dont want to give them cheap price if they have draws. Vs fishes I usually bet pot or overbet to have around 1 SPR on the turn to apply pressure to their draws or weaker made hands.
It makes sense to me to bet 1/3 with the whole range on sites with HUD or non-anonymous sites where good regs can punish that but on Ignition people will not notice that I only bet big with top of my range.

When you bet with hands such as KJ here (with backdoor equity) and similar - do you go for tripple barrel if your equity increases on the turn (lets use hand above as an example but the turn card is Tc)?

BTW is 4x preflop ok or is it too large? Do you have one sizing or do you vary based on your hand strenght, villain etc.?