So Day 1D of a Big Tournament. About 500 entries.

Start with 25K I really did Not get anything Big going,
have 30K, AVG 46K

Blinds 400/800/100.

I Open Utg with a rel. Tight Image, People see me showdown J9s UTG Once.
Have 3bet Coupé of Times but not 1 4bet in 8hrs of Play.

I Open KK 1600 UTG, folds to Decent Player in BB, who really
Is Not out of line preflop and likes to defend.

Villain 3bets to 4200. I have about 28,5K behind, he has 60K or so.
As I have Not 4 bet once, I thought I would fold out 99-JJ,AQ Here, Maybe Even
QQ and AKo. I decide to flat to Maybe Stack him on Low boards

Flop comes J57 and he Checks. He has Been passive a Lot of Times and really
Likes to small ball and has a low cbet%. Pot is 9,700 I bet 4,500 for value thinking he calls TT,QQ and Maybe AK. He calls. Pot is 18K now and turn comes a 9. He checks.

Basically any bet Here I am committed, I have about 20K left.
What to do Here. Check back and Pot Control in Case he has JJ/AA and so he might make Bluffs with AK in river. Or bet turn/Shove turn?

Is preflop vs this villain and my Image Better than 4bet?
And what is optimal on turn?