I expect you will make significant gains over the next 12 months. Starting with a base of 238W and following a structured training routine, I think 300W is a reasonable mid-term target to aim for. But not in 6 weeks! I wouldn't even think about short term gains like that. You will probably measure well over 250W on fresh legs and with 6 weeks of quality training, but consistency is what you are really looking for. Beware of "newbie" over-training. A lot of guys smash themselves really hard for the first 6 months or so, see some pretty impressive gains and then completely blow up! So don't fall into that trap. It's a bit like crash dieting. Make sure you build up the training load gradually at a sustainable level. Follow the advice on Trainer Road carefully and don't try to accelerate your progress. Take your recovery time seriously.