It's really a personal judgement call. With only 20 BI's I would suggest 'taking shots' as oppossed to just jumping in. Example: if you play 4 tables, play 3 tables of 10NL and 1 of 25NL to sort of ease yourself into the game. I'm a huge bankroll nit so I personally wouldn't be going up to 25NL without 30BI's minimum. But if you do the take a shot approach, you could log another 5K hands or so at 10NL while getting experience at 25NL. Everyone will give you different advice on this subject though so this is just my 2 cents.