I'll probably do just what you suggest, very soon. Because I just don't learn from experience.
Of course, we can get things going early in our heated propagators. They will germinate fine but then just sit there without growing very much until late March or April.
As well as heat, almost all plants need light. I've tried with extra lights ('daylight' energy saving bulbs) and doing everything I can to get the new seedlings going.
In the end, boring though the answer is, I've discovered that you might as well leave most things until March or even April, as once they germinate then they will grow away much more strongly, overtake the ones you sowed in January, and make almost no difference in when they mature.
It' s immensely frustrating for all of us keen gardners, but really it does pay to wait.

Sorry Sunshines but I agree with Bertie...

agree too unless the plants you grow are fully hardy when you may be able to getthem outside week or two earlier than normal.

I started tomatoes off in January under a prop a few years ago and then transferred them to the windowsill when they were too big for the prop'. They grew fine but I don't think they ended up fruiting any quicker than the ones I planted in March/April

Yep....I agree too.....if you then put them on the windowsill, mine seem to end up too leggy searching for the light in the short days we have.

I have learnt to curb my excitement as it is just not worth the hassle. It is far too soon.