When do I suppose to plant begonia tubers?

Mine went in a shallow tray some weeks ago until they got shoots...that took a few weeks...now they are in pots.

Thank you, looks like it's too late to put them in. Is it worth buying (begonia) plug plants? Is it too late to pot them on?

I really don't know - can you get corms with leaves in pots?? It wouldn't be too late to buy them at the stage mine are at, which is about 4" tall - if you can!

Thank you very much.