From everything I’ve read and what my doctor emphasized, once you stop Tymlos you really don’t want to leave a gap before starting a bisphosphonate because the bone you built isn’t “locked in” yet and turnover can ramp back up pretty quickly, so while it’s not like you lose everything overnight there is a gradual reversal that can start sooner than people expect, which is why most recommendations are to start something like alendronate or even an infusion like zoledronic acid basically right away (next day or within a few days at most) to preserve those gains, and if there’s any unavoidable delay (insurance, scheduling, etc.) it’s worth pushing to shorten that window as much as possible or asking your doctor about a temporary bridge because the whole goal is to prevent that post-Tymlos drop-off from even getting started rather than trying to recover lost ground later.