About starting it later or when you meet a problem, either find out which quest it try to complete and do it manualy and then the profile will eventualy pick up where it should be or delete what you think is too old for your level, make sure you either complete the chain quest or delete it fully or the bot will keep bugging, these profile are easier to start in early level, if you have no knowledge on how to debug a profile it can be hard for you to start them in later level, just open wowhead.com and try to figure out whats its trying to do or complete it will eventualy help you to understand the mechanism of the profile itself. I can tell you that most of the time when it bug its very simple to unbug it if you have some really basic knowledge. Open the profile and see the mechanism its very easy to figure out, you will be able to debug yourself anytime there is a problem from it. Its nice when you reach lvl 60 to see 200 quest as achievement plus it actualy level faster or more naturaly than any grind profile ( less risky to get banned overall)
Hope it help.
Zuruss