>>1 Fun fact: The friend zone is an illusion created by the people who give up halfway into committing to a relationship. It is an excuse that embodies the level of a relationship that is either much too unfamiliar to proceed to romantics, or so familiar that one party becomes wary of intentions.
Technically speaking, timing shouldn't make a difference. It isn't a matter of trapping your partner during a specific time window when they're guaranteed to say yes, and if you thought it was, would you really be satisfied with earning a relationship in that manner? The answer "I'd rather just stay friends" is just a nice way of them to not reciprocate - it doesn't mean you've overdone the friendship thing. In fact, saying that is inherently stupid - why would being a great friend
hinder your chances?
If anything, your chances are best when you know each other the best. This is the answer for the long term, though. Some people like to make it a gamble by making their intention known and asking someone out really early, as early as first meeting them - the problem there being that the other party might want option A.
The others in this thread have given you advice on how to read a mutual attraction, but do know that it's usually not such an ideal situation. Look for those things, but don't expect them, and don't be presumptuous if you think you see them.
If there was a correct answer to your question, that would mean all people are the same. Don't fall for that misconception.