Villain is 23/14/4 over 250 hands, RFI on button 30%. C/R on the flop, or wait? As played what's a good river size bet? Is this a good spot for an overbet? Thanks-

SB: 148.46 BB
Hero (BB): 205.42 BB
UTG: 100 BB
MP: 72.36 BB
CO: 203 BB
BTN: 107.02 BB

SB posts SB 0.5 BB, Hero posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 9 J

fold, fold, fold, BTN raises to 2.5 BB, fold, Hero calls 1.5 BB

Flop: (5.5 BB, 2 players) J K 9
Hero checks, BTN bets 2 BB, Hero calls 2 BB

Turn: (9.5 BB, 2 players) J
Hero checks, BTN checks

River: (9.5 BB, 2 players) Q
Hero?

If you call flop, donk bet turn. Why?

Villain has passive tendencies.
Their flop bet was small, and non-committal.
A thinking player can see the turn card nails your range.

That's opposite of what you want for a check/raise line. It's getting checked through too often. Leading your strong hands there is more +EV.

As played, I see a bunch of viable river lines.

A big overbet targeting Tx.
A check raise targeting Tx, knowing it would be hard to get called by Kx or Qx after leading on the 4-straight (your flop-calling range has few, if any, natural bluffs on that runout)
A blocker bet/raise/reraise kind of thing. Like you try to get a small amount of of two-pair, hope they raise Tx so you can reraise.

Like your line so far.

Now check raise... unless he bets big then call.

Thanks for the very detailed breakdown, lots to think about here, much appreciated.

x/r flop

Seeing turn x/x just makes me cry

Haha goes to show he didn't have much to begin with. Not sure how to get something out of a nothing hand.