How many hours a day should I spend reviewing charts with my busy schedule?
How many hours a day do you expect a pro golfer practices?
How many hours a day do you expect a pro musician practices?
How many hours a day do you expect a (insert any other elite performance activity) practices?
That's how many hours a day you should be practicing.
Trading is an exceptionally difficult endeavour. The edge is very small. Success requires skill and expertise. This is a performance activity and you're competing against people who work at this full time.
How many hours should you work at trading each day?
As many as you can.
Will that be enough?
I can't say. Your results will provide that answer. And if the results are not what you desire, then look to your levels of passion for this game as to whether or not to continue pushing forward harder or smarter, or to find another path in life.
Hope that helps,