I do tuberous begonias - and I'm not starting those until mid-March! they all really need a prolonged chill down. Personally, I think she's jumping the gun a bit by a couple weeks. I keep mine in sawdust in a COLD but not frozen closet. I mist it down lightly before I put the tubers in it (have cannas in there this year too... haven't checked on them yet) I inherited this bag of perfect stuff from my dad, and at many points he'd innoculated it with sulphur powder though I haven't been able to get my hands on any to re-do it the past few years. If it's really a dry winter (the bag is an old feed sack) I mist the outside of the bag once or twice then put it into a garbage bag. Gives it just the right amount of moisture without causing stuff to mold.

-Marie

Yep- I agree with Marie- I find it best to wait. I don't have enough room under the lights to keep them happy that long!! They get all leggy and weak.
Maybe your friend has a trick up her sleeve....

She is definitly jumping the gun (take it from the expert who has jumped the gun way too many times and has learned the hard way.) Dahlias- especially the dinner plate varieties- do better when they're planted directly outside. They're going to be so leggy by the time its OK to get them out (5.10.07!!) that she'll have weak plants that will melt in the sun- and be whipped in the wind.
I grew about 40 dahila plants last year- I had my best year because I did not start them inside.