Posted: 23/01/2015 at 09:24
I'd agree with David that beating nature is hard to do but I also know just how itchy I get in January to see things growing! In practice, the early-sown seeds of most plants don't really get you ahead of the game - the later sowings nearly always catch up and (to be honest) are often healthier..... BUT it is just so nice to see something green happening as early as possible! So, as long as you don't expect miracles from your propagator I'd say go ahead and have fun with it. And there are definitely a few seeds that do benefit from early sowings.
But you do need to think about where you put the baby seedlings once they've germinated - they won't need heat any more but they mustn't be cold, and they'll need lots and lots of light. Have you got anywhere that might work?