Super Thursday Bluff

[AceHiStation]

Reads on SB: Fairly solid, seems to be willing to make a laydown... has made all-in bets, has folded to all all-ins so far. I haven't seen him make a weak bet like this. His last BB he was dealt ATo and checked with 3 limpers and the SB completing. He bet half the pot on a 66T flop and called an all-in raise and beat KTo.

Reads on CO: Doesn't seem to understand gap concept. I make this play mostly because of him.

Going to the flop I decide I am going to continuation bet and if CO shows aggression I will lay this hand down. SBs bet seems to be a weak ace or a draw. At the time I put him on very weak ace(A5). When he underbets the flop I decide I'm going to attack this for a few reasons.
1. CO is unable to make a play without a legit hand as he has to risk facing both my hand and SBs hands and we both have shown aggression.
2. SB has to respect my raise as I was PF raiser and we are 3-handed, no way would I bluff with a big stack behind me in CO.
3. SBs bet shows a lot of weakness.

I am very confused as I have seen SB take his time in his decision making before, but nothing like this. Is this a play any of you make? What do you put villain on? Is this too early in the tournament to risk my stack?

Party Poker No-Limit Hold'em Tourney, Big Blind is t150 (10 handed) converter

MP1 (t1865)
Hero (t3320)
MP3 (t5439)
CO (t5052)
Button (t3635)
SB (t3325)
BB (t1194)
UTG (t2595)
UTG+1 (t2205)
UTG+2 (t3759)

Preflop: Hero is MP2 with 4[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/club.gif[/img].
<font color="#666666">4 folds</font>, <font color="#CC3333">Hero raises to t400</font>, <font color="#666666">1 fold</font>, CO calls t400, <font color="#666666">1 fold</font>, SB calls t325, <font color="#666666">1 fold</font>.

Flop: (t1350) A[img]/images/graemlins/diamond.gif[/img], 7[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">SB bets t250</font>, <font color="#CC3333">Hero raises to t800</font>(Activates full time-bank and calls with 1 second left), CO folds, SB calls t550.

Turn: (t2950) 3[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
SB checks(Uses entire time left), <font color="#CC3333">Hero raises all-in</font>

Results in white below: <font color="#FFFFFF">

SB folds(Uses entire time left again).
Final Pot: t5070
No showdown. Hero wins t5070.

Post-hand chat:
matthew432: ak?
AceHiStation: yeah, flush?
matthew432: aj
AceHiStation: figured you were gonna outdraw me... diamond turn slows me down
matthew432: shouldnt have called flop</font>