What consistency should flan have when it is removed from the oven?
It will firm up a little bit during chilling, but not much. It is certainly supposed to be firm enough to keep its shape on its own when taken out. 

If you have baked creme caramel or cheesecake, then try to get it to a similar consistency as these. If you haven't, you may want to use a roast thermometer. The final temperature (assuming a traditional flan without starch or flour) should fall in the 85-90 Celsius range.