Not knowing the nature of the break (other than it was a compound fracture), it could be anywhere between 6-16 weeks. If it's an ulnar or radius break, that's usually between 6-8 weeks. If it's a carpal break, that's between 10-16 weeks.
The previous break of the same wrist may lead the docs to insert a titanium rod or metal plate, and depending on what they use and the atrophy involved, those measures can either speed up or slow down the healing process.
FWIW, Gary Washburn tweeted that the Cs expect Delonte to miss 3 months. From what they said on CSNNE, they have an MRI schedule for Friday morning, so it's all speculation until then.
Whatever the case, Delonte is being severely tested and we can only hope he responds positively to this adversity. Unlike the suspension, he won't have the solace of the court to help him make the right decisions on a day-by-day basis.