Yes is the short answer, it is too late, but if you just want to give a very light trim in a couple of places, you can do that now. The best time to reshape and prune these is round May/early June - doing it now may encourage too much soft new growth which won't harden off in time for winter.

If you prune it now you will cut off next year's flower buds that have formed on the ends of the shoots. If this is OK then go ahead, but best to prune immediately after flowering. You can prune Camellia right back to the thick branches and they will sprout lots of new shoots. You may not get flowers on these shoots for 2 or 3 years. So you need to decide if the plant needs a trim or hacking back! If it's growing over a path, etc then you have no choice but to cut it.