As Tofu Pup said, if you seriously want tipped ears keep it up until at least 1 year old. If you are less committed, keep it up as long as you can stand it. Then take your chances. It is a pain!
That being said, you can eliminate some pain if you are using the right products and techniques.
I screwed up in the ear tipping myself. If ever I get another Sheltie, I will have the proper materials on hand - starting with Detachol - for removing old glue. Bacca's ear gluing ended prematurely when I had to cut out the fur between his ears because I had nothing to remove the old glue with. Once all that fur was cut out, there was nothing else to reglue! We were pretty much done at the point.
I would also investigate Japenese tape. Easier than moleskin and better than glue, I think. People who have used the tape might have better opinions.
If you are not showing, gluing is just a matter of personal choice. Just remember though that the ears are not just about the tip of the ear, but also the set of the ear itself. My Bacca's ears are tipped - oh yes! Too much so because he has hound ears. He needed bracing between his ears to keep the carriage up. That's where I failed.
Hope this helps!