When do you gank as lee sin?

Hello can anyone give me tips in ganking and jungling everytime im doing camps in jg top lane is pinging saying gank the enemy but by the time i get there theyre already gone. any tips on good balancing of jungling and counter jungling and ganking? first time jger btw my jg champion is lee sin and everytime i try to gank if my q miss or hit a minion, the enemy has already backed so any tips on when to gank?(especially on lee sins q and what to do next if a gank fails) thanks!