On a site execute, utility comes in three layers. Smoke first (deny vision), flash next (blind defenders), molly last (delay rotators or post-plant).
Smoke timing: throw and wait 1-2 seconds before you push. The smoke needs to land before defenders see you committing. A premature push gives them a free pre-aim.
Flash timing: pop the flash as you take the corner, not before. A flash 5 seconds early is no flash. Pop-flashes detonate over corner the instant you commit.
Molly timing: drop a molly on default plant only after your team has site control. A molly thrown during execute is wasted utility — defenders aren't in the burn zone yet.