Building it up before playing with it is sort of a waste of time.
A) You play with it and have a losing streak, so you have to go back and play more freerolls.
B) You play with it and win. Now you can keep playing $ games which are substantially more profitable.
C) You save the money until you have a bigger bankroll. Now you can do steps A or B.
Step A is like step C except with A you are guaranteed to spend the least
amount of time in freerolls before you start playing/winning real money
games. So really, C is the worst (unless you need to spend more time learning the game).