Is it too soon?

When you put them out last year did a frost get to them?

I know its very tempting to start early and does work for some people but if your putting them out into a unheated greenhouse then a surprise late frost can catch you offguard and your back where you started

If I was you Id hold on a little bit first

I got a bit exited last year and sowed a lot of my crops way too early, needless to say I regretted it and my later sowings soon overtook them and produced a better crop, be patient and you will be rewarded

I would leave it until at least March before sowing most things - but as a poster above says, the back of the seed packet is a good guide. If you're on an exposed site, add on a week or two.
You can amuse yourself by covering beds with fleece, whcih will warm the soil up slightly quicker bit to be honest things seem to catch up in the end. And as somebody else has said, the day length is important too.
Tidy up your pots and seed trays for now and get your labels ready.

Like you I have a bit of a problem with patience. I think it is the dark nights and the winter dragging on. Getting things started feels like the spring is (at least symbolically) here!
I have tended to plant things at the earliest oppertunity and as most have said here, lived to regret it with weak leggy plants that get overtaken but their later siblings.
The exception I have found is chillis. I still tend to start them in Jan in a heated propagator and once germinated they go on a warm, light window sill. Some of them occasionally go a little leggy but I leave a good inch and a half spece at the top of the pot which I can top up if needed and they rapidly sprout new roots from the buried segment.
In my heart I suspect that a later sowing may do a little better but I have always had a good crop from my chillis with healthy plants and it definately benefits the others by distracting me long enough for spring to truely get here!
I have managed to be more patient with the others, especially toms, but the chillis have become my start to the year that I can't quite give up!

I'd agree with all the stuff about light and waiting a few weeks, but would also say that despite growing lots of great toms I've never got much in the way of peppers. Chillies are another matter...

I decided that last weekend was the time to start when all my overwintering chillis started putting on new growth so hopefully the new ones will do ok.

Indeed! The first night Mrs K said she couldn't sleep - curtains closed in bedroom, but not in my study - worries about the Roses outside my window breaking into bud too early, and monstrous weeds ...

But I reckon I need several lights before I manage to get the sub-station to trip and the Boys-in-Blue come round, although the fertilizer I bought with it is called "Canna", so my defence is going to look pretty shaky ...