What is the minimum wait time between HIFU and PDO Thread Lift?

There are no studies specifically addressing this issue to my knowledge, but that said, it is best to wait at least 4 weeks before doing another treatment whose purpose is, at least partly, the stimulation of the healing cascade. In other words, you lose some of the collagen-stimulating effects of one treatment if you start another treatment before the first is through the healing phase, 1 month. In my practice I perform any energy based (EBD), i.e. heat, prior to threads or, if threads done first, I wait about 6 months after to avoid weakening my precious threads. Ideally the EBD treatment is performed first, then immediately (same day) or 2-3 months later, the thread lift is performed. This allows maximum collagen stimulation from both procedures and avoids heating, and thus weakening, your threads.
EdWoodMD