Modern Canon DSLR batteries are lithium-ion, so the old “charge it for 24 hours” advice does not apply. That was mainly for older NiCd batteries that could suffer from memory effects.

For a new battery, the practical advice is simple: charge it until the supplied charger indicates it is full, then use it. Leaving it on the charger longer won’t improve it, because the charger stops charging once full.

It may also arrive partially charged—often around a storage-friendly level—so you may even be able to start shooting right away if you want.

A full first charge is fine, but not required for battery health. Two hours may be enough if that matches the charger/manual, but the right rule is to wait for the full-charge indicator rather than timing it manually.

If you’re unsure, check the camera manual for the expected charging time.