All episodes are presented from T's perspective. Tony enters the restrauant, but the director puts him temporally displaced, actually watching himself seated, to remind us of that fact.
Meadow is upset; she needs to talk to Dad (after all, she is a Mob lawyer) perhaps to warn him. Her agitation makes her attempt to parallel park difficult.
A man with a form-fitting Member's Only coat (you remember those - the 80's Journey song about a small town boy helps us notice that) Maybe he is settling a score for Phil, who was locked with him up for 20 years, and he only has wardrobe from that era - and is short on cash, hence Phil's plan "B". He enters the restraunt, following AJ, but Tony dismisses him since that tight coat could not conceal a weapon (Tony would pick up on that) and the guy uses the bathroom. That's where the gun is.
Tony is seated in the direct line of fire from the bathrooom, which is excecuted at the moment he sees his daughter enter the restaraunt - the last thing he sees. Again, since the show framend in his perspetive, the screen simply goes blank.
We can assume that by the time Meadow gets to the restraunt door, Tony looks at her, not seeing the .380 directed at this temple. (A scenario not unlike Phil, who is admonshing his wife about a perscription pick-up when he is killed.) He is reflecting on AJ's comment to remember the good times, and he is glad to see Meadow. Then the shot is fired.
Tony's last moment is enjoying his family, remembering the good times, and feeling the relief all parents feel when first seeing a child that is overdue. Not bad for a guy who had it comming.
Remember a previous episode: you never hear the bullet that kills you.