[pzhon]

Overall, your plan looks ok. However, you are starting with a bankroll that is too small for those levels.

Twenty buy-ins is quite aggressive for playing SNGs, even at low stakes. SNG players usually recommend having much more than that.

Twenty buy-ins would be quite conservative for low stakes NL cash games, if you have a decent winning track record.

These depend on your win rates. For the same number of buy-ins to be appropriate, your win rate in big blinds/100 in a NL cash game should correspond to a ROI of 4 times as great for a 9 or 10 player SNG. That is, if you feel 20 buy-ins is right for you in NL with a win rate of 15 big blinds/100 hands (achieved by many players), then 20 buy-ins is right in SNGs if your ROI is 60%, which no one sustains.

It sounds like you are applying "20 buy-ins" out of context. You probably want to use a larger number, such as 50 or 100. Rather than a fixed number, you should use a number of buy-ins which increases with the stakes, since you need more buy-ins in tougher games where your win rate is lower.