When and how to start indoors in spring?

I tried saving dahlia tubers this winter. I used Poochella's instructions-I figured she lived near me so it was likely a technique that would work for me. I last checked them about month ago, all was well, now I find many have rotted or have a bit of rot starting on the end. The biggest ones are doing the best.
I just bought some grow lights for seed starting. I was never quite sure when to start my dahlias growing, Poochella mentioned April. I was not sure but I assumed this meant starting indoors in April, as in the Seattle area the soil does not warm up until June usually.
My thought is to put these tubers, each in a pot or maybe all in a big flat, under my grow lights, and just try and grow them now, rather than wait another month and have the rot spread. I am guessing that once they start to grow they can fend off the rot.
what do you all think?