Pricking out toms

I understand the general rule for pricking out is to wait until the first set of true leaves appear.

I usually follow this for tomatoes  but I've read somewhere (twice now) that research has suggested the optimum stage for transplanting is six days after germination, at which time only the seed leaves show.

In reality I probably prick out anything when it suits me or when I have space for them, I'm not scientific,  more a bumbler

What do you think?

I agree, you're more of a bumbler.
I do it when they're big enough to handle as I'm so cackhanded.

I usually prick out within 24 hours of germination for things like toms, chillies, aubergines and anything else that germinates in the heated propagator. They would go to leggy left any longer in there. But for things that germinate in the polytunnel. I’m like you and prick out as and when I can be bothered. But before anything gets to big.

I also agree you're cackhanded  just to be unified in our response   (not that I have a clue in reality)  Together (heaven forfend) we could cackhandedly bumble .....or bumble cackhandedly, we would have to argue over precedence  

I do prick out once the first true leaves appear, but also move things off the heat mat as soon as germination has started to stop them getting too leggy. It feels to me (no scientific evidence, just observation - assuming the memory is right!) that everything is a little slower to move on if pricked out any earlier.
But having had no germination of Gardeners' delight last year I sowed all of the packet this year and of course now have a pot full of seedlings. I'll do some now and leave some until they have true leaves and then see the difference.

Having given this a little more thought.............with tomatoes, courgettes, cucumbers, I sow 2 seeds in a module and bung them in the propagator. The module size depends on the size of the seedling I hope to grow. Tom modules are smaller than courgette modules. I prefer 4, 6 or 9 joined modules to the 24ish ones as they're easier to handle and you don't have to whip all of them out of the prop when only a few show life.
If both seeds in a module germinate and look healthy, I may remove one and replant it, but, generally, there's enough room in the module for the seedling to grow without needing immediate transplanting. Puny seedlings, sharing a module are pulled up or snipped off.

^^^you heartless creature, poor little seedlings

My seedlings come out of the h/prop and onto a window sill as soon as I see a bit of green.
They get potted on when they have their true leaves otherwise to me it looks like there's not much below the compost to call roots.

I'll sometimes just scoop the seed out once I see it cracked
Tom's I never wait for the true leaves though I much prefer sowing single seed in a module... prefer that to pricking out but often don't have enough space.

I do prick out once the first true leaves appear, but also move things off the heat mat as soon as germination has started to stop them getting too leggy. It feels to me (no scientific evidence, just observation - assuming the memory is right!) that everything is a little slower to move on if pricked out any earlier.
But having had no germination of Gardeners' delight last year I sowed all of the packet this year and of course now have a pot full of seedlings. I'll do some now and leave some until they have true leaves and then see the difference.

I ended up with three pricked out at the first true leaf stage and three at the seedling leaf stage. By the time of planting out I'd lost the labels  so didn't know which was which, but as they were all the same size I guess it didn't make much of a difference.