You don't say where you are. Dahlias are not hardy, so if you are in a zone like I am (Northeast - zone 6) if you did not take your pot in over winter, it's not going to come back. Otherwise, I'll let someone else chime in. I would think once the soil in your pot warms up and the temps in general in your area, the dahlia would start sending up sprouts.

im in the uk. i know they arent hardy, and have protected mine from frost. like i said, the tubers appear healthy and firm. we have had a lot of cool nights here that has slowed some plants down.

They should be eyed up and sprouting by now... It's hard to miss that when checking the tubers. I'm assuming you've left the pot in the sun? Night temps might slow the growth, but not keep it dormant.

Personally, I'd replant them in an out-of-the-way spot 'just in case' and plant something else in your pot to enjoy this season.

yep, the pots in the sun, its in the porch now to avoid the chilly nights weve had in the uk . no sign of buds... but healthy tubers.