When can i leave the poker table?

In a cash game, you can leave after any hand (while you also can in a tournament, there's little reason to do so as long as you have chips since the chips themselves have no intrinsic value.) Note that leaving immediately after winning a big pot is often considered poor poker etiquette (it's a different story if you'd told the table previously you had a firm leave time and the last hand just happened to be a big win...the others might grumble a bit at your luck but that's all.)