Last year I took cuttings as soon as 28 days, and as long as 87 days, so it greatly depends on the variety. Cuttings meant that the sprout had grown 3 full sets of leaves, so obviously there were signs of life long before that.

Once in pots under lighting with some watering, you should see signs of life in a week to 10 days for most...but some may appear lifeless for weeks. Patience is a virtue.

As far as depth, I've always thought of it as the distance to the crown. Not that it makes a huge difference, as the crown shouldn't be far away from the side of the tuber. If you're placing them tip down (e.g. standing up on their ends with the crown up) then you don't even need to bury the tuber. Again, last year, most of my cuttings were taken from tubers whose crown was completely out of the soil.

Cheers,
Russ

I am a dahlia newbie but ordered some from The Dahlia Guy. I haven't received these yet. Walmart had some so I bought a pack and potted them. From what I'd read about how to store them, it seemed the Walmart tubers had not been properly prepped last fall. As such, I didn't have much hope. Maybe three weeks later, all three Walmart tubers have green growth. I ended up with two tuber packs completely buried and one had the stem sticking out of the dirt a bit. They all look alike now. The buried ones came up first.

I was hesitant to grow dahlias in the past, due to having to dig and store them in the fall, but I now think it'll be worth the effort.

NOW, I just need DH to build some trellises and figure out how to protect them from bugs...

Some dahlias take WAY longer to sprout than others. I have one that doesn't wake up until almost June but by July/August it's blooming it's head off at about the same time as all the rest.
Ellie