A 24 hour plant that has already grown 2 inches is in trouble.

It is stretching for lighting.

You better worry about that before needing more room for the roots. As it stretches for light, it isnt growing any roots anyhow.

As far as transplanting, a 3 - 5 gallon bucket is way too big at this time as far as I would do it.

You have way too much soil to water when you water and the water around such a small plant will dry up first, while the rest is still wet. Then you get caught in the watering around the plant game and that isnt how you want to water.

If I were to transplant, I would water the soil well and pack slightly. Turn plant upside down and coax out soil in tact, place in new space, fill sides, water and be done.

I would give it at least 7 days before transplant...but if it stretches much more you wont have to worry about it anyhow.

LIGHTS!