My mother very successfully used the original tubers she started off with,for over 30 years!! The first signs of buds probably won't begin to appear until at least April/May depending on how warm the area is they are being stored in. It could also be as late as June,because,the tubers seemed to take longer to bud once they were older. As long as they have been stored in a dry environment,don't worry about them,they'll come on when they're good and ready. Good luck
I put mine (40 of them !!!) into a warm conservatory in January. Some are 6" tall already and some are just starting to show. First showings were probably after around 4 weeks.
I have recently planted my Begonias outside in containers here in Glasgow......but have some in reserve still wrapped in newspaper in the garage! Can't wait to see them grow!!
How should I divide them? Is a sharp knife alright?