League-of-legends – During the laning phase, when should you take your lane’s turret

You never stop to try and last hit the minions, except when you're playing support; then you'll leave the last hitting to the carry you are with. But at times it's good to push minion waves to the enemy tower (either using your spells or starting to auto attack), since enemy towers can and will deny gold (and XP - only when your opponent isn't there) from your opponent. But you always have to look at the map when you are going to push, because overextending and dying to a gank is worse then letting your lane opponent farm.

Conversely, if the enemy is pushing his minions closer to your tower, you can start auto attacking the minions to get them down faster, but even while auto attacking you still need to watch minion hp so you can get the last hit.

Short answer is if you are winning your lane (like killing the other champion several times), take the tower when your minions manage to destroy it on their own.

Reason: You want the laning phase to last as long as possible since you are winning the lane, your advantage of your lane versus their lane is only going to continue to snowball to an advantage for your team.

Guideline: Varies for different lanes, but I would say don't take the turret before you reach level 11. By this time, you have the second level of your ultimate and can make a bigger impact on the rest of the game. Generally if your team is ahead or even, taking the outermost tower is a certainty to occur. I might make an exception for mid-lane as that middle tower gives so much control over the map and you can really start controlling their jungle to make up for if they freeze the lane and try to deny you.