You should create a Demo option and not directly require a deposit, because you are just starting out and it does not give much guarantee of making deposits so happily, the option of no registration does provide a lot of anonymity, although you should also implement some registration, many players like it that option.
Addition of demo will help more gamblers learn about the poker. There'll be people who like to spend, but doesn't know how to play. Demo will give a learning and let users experiment the game. It is something same as providing dummy tokens by trading applications to try trading.
I don't think you would learn anything playing with dummy tokens, maybe you would learn a little bit the rules but it will not help for strategy. No limit texas hold'em poker rules are quite easy and what makes the game interesting is the strategy.