no good answer due to normal variations in physiology and variations in the specific person's quality and severity of addiction but in terms of timescale I would say a day-ish? Would be better to ask an ICU RN or MD. At my level and specialty of care (acute psychiatry) and assuming the pt has been screened appropriately by the ED to not already be in high acuity withdrawal (needs medical or ICU) we're generally not talking minutes to a couple hours but we're also not talking a week. The scale we use to measure is called the Clinical Institute Withdrawal Assessment.

Depending on the half-life of the medication used for the taper I'm reassessing that score either every 4 hours (ativan) or every 8 (phenobarb). My unit usually does phenobarb because it requires less frequent and precise assessment due to the elongated half-life. And I can always reassess ahead of schedule and give 1 extra dose as a standing PRN order without even needing to call the on-call MD if they're having breakthrough symptoms.

Also keep in mind that it's not just mortality we're worried about. I can't make withdrawal fun but I definitely don't want it to suck any more than it has to. There's also a lot of permanent but nonfatal damage that can happen in the meantime. And it's actually also an issue of my safety and that of my coworkers. My subspecialty is actually specifically the management of violence and drug withdrawal is an item on MOST violence risk assessment scales. Actually the only one I don't see it on irrc is the BROSET and that's just because it's a rapid 6-12h tool and the CIWA is already addressing that under the agitation and paranoia items at that time interval.

The paranoid delusions and audiovisual AND tactile hallucinations are no joke. One of the COMMON reasons I get called to medical units for backup is CIWA patients because we can't take them until they're on the tail end of a high dose taper but the medicine nurses aren't always equipped to address the psychiatric symptoms and there's more equipment available to throw / swing at them.