When we reflect is up to us (generally, the more often the better). And there is good reason not to accept delays.
It seems to be a fairly common tendency to postpone reflecting on what you want to do with your life to some later time: when you have the requisite leisure, say, or when you've made sure that your career is well on its way. Sometimes people who have this tendency make that decision expressly, but mostly it just remains implicit in what they do (and in what they don't do). But it's easy to see the error in this choice. If you postpone reflection on your character and on the whole of your life in order to do something else first, then whatever it is that you do first has a higher priority for you, whether you admit it even to yourself or not. What's worse: because you haven't even thought about it, it is very likely that your choice is a result of some influence (who says that building your career is the best and most valuable thing to do with your life?) rather than your own considered views. In other words: whatever reasons there may be for choosing as you did, they were not really the reasons for you to make that choice. There may always be better or worse choices for what you could do with your life than the one which you actually made — but not choosing at all is certainly one of the worst.
If, on the other hand, you do choose, and if you take care to reflect well, the reward will be a sense of direction for the whole of your activities, an overall state of control of your life, a calm and conscious enjoyment of the best possible condition you could be in: a state of excellence, of having actualized your potential, of happiness that grounds in your own self and not in accidental turns and twists controlled by chance nor lucky gifts from fate and fortune.
But obviously it can be stable only if you do something for it. It needs a certain constancy and some determination to keep up reflection; it's essential that you never cease to think about your life afresh, to scrutinize yourself and ask what you can do to get more closer to becoming the person that you want to be, to check if all your actions, views and feelings correspond to what they should be if you'd reached that goal. There is no such thing in life as a premature decisive win. Once you are committed to a life of excellence, with every new day you will have to find out where you stand and work on steadying and improving that current status. Every time you don't, you'll just fall back and have to win the lost ground back in what will be an uphill struggle. It is wise to not get there right from the start. You can avoid predicaments like that by never tolerating a delay in that vital reflection on your life and character. Take care.
