Sowing seeds out of season

Ok, I know Veggie does this...and I obviously do occasionally but on other social media I'm seeing people start climbing French beans, squash and all sorts. I have got some bush Tom's going, o just had to start a couple of flowers. Really worried that I've wasted my salvia seeds as stuff grown too early and left inside can often lead to leggy weak seedlings.

I know it's only the cost of a few seeds - but I don't like wasting them if I have to buy them as the postage hikes up the costs. I've given up sowing lots more than I need as compost is precious to me at the moment too. I ran out of pots last year - I'm not going to garden centres. I'm also on a water meter - I've felt it's a waste to use all these resources on growing too many and wasting stuff on chancing my luck and then it going in the compost at the end.

I get that if you don't experiment you never learn - but climbing French beans now is madness or is it?

What early sowings have worked for you? How soon is too soon?

Salvia nemorosa should be OK, they are hardy down to -20C. If they die I can just send you some more seed   I've sown quite a few flower seeds already and will be sowing even more at the start of February. They don't go under lights, just on a sunny windowsill or in the greenhouse if it's warm enough.

In February I sow cold hardy things like brassicas, lettuce, spinach, peas, spring onions and shallots. They stay in the greenhouse, maybe with an extra covering if there's a sharp frost forecast. Also some early carrots in pots.

Beans, not until April in the greenhouse at the earliest. Can't imagine how big a January sown squash will be by May!

There is a Youtuber who grows early climbing beans, courgettes and cucumbers quite successfully, but it's a lot of extra work (heated conservatory, bubble wrap, fleece etc.).

As you know, I sow out of season to test how far ahead, or behind the game, I can be. I only experiment with seeds that I have plenty of and won't miss if they fail.
Apart from the early tomatoes, I have courgettes, cucumbers, DFBs and CFBs in the propagator.
On 20th November, I sowed/poked some Bijou Mangetout seeds into some emptied tomato pots in the GH. They're 6-12" high now.

Only gamble if you can afford to lose.

On Veggie's recommendation I too sowed bijou peas also some green hurst peas on 21st Nov in a cold greenhouse. Both are growing the bijou have overtaken the green hurst. I shall probably do this again. The toms, aubergine, chillies and sweet peppers are a first time for me this early in the year. Next sowing spree will probably be in February. Lack of warm space is the problem.