It varies a lot — that is the honest answer, and the more useful question is what it varies with. Here is what actually moves this timeline, in either direction.
Two two-year-olds in the same room, starting the same week, can be on completely different timelines, and neither is doing anything wrong. What follows is not a way to guess a number — it is what actually shifts the timeline, so you can tell what is worth adjusting and what is just who your child is.
A child attending five consistent days generally builds familiarity with the routine faster than a child attending two scattered days, simply because there are more repetitions of the same predictable sequence in less calendar time. A sporadic schedule can make every drop-off feel closer to a first drop-off.
A room with one or two steady, familiar faces lets a toddler build trust in a specific person. A room with frequent staff turnover resets some of that trust each time, regardless of how many weeks have passed on the calendar.
Some two-year-olds warm up to anything new within a day or two, as a general trait that shows up everywhere — new food, new people, new places. Others take weeks to warm up to everything new, not just daycare. This is who they are, not a sign daycare is a bad fit.
A child who has already spent time with a grandparent, a regular babysitter, or a familiar sitting circle has some evidence that separations end with a parent coming back. A child whose very first sustained separation is daycare itself is learning that lesson for the first time, which understandably takes longer.
To some degree, yes — a new room and new faces are a genuinely new adjustment. It is often shorter than the very first time, because the underlying lesson (separations end, and you come back) has already been learned once.
Not necessarily. Temperament varies child to child even within the same family, so a sibling's timeline is not a reliable prediction for this child.
The combination that shows up most consistently is a steady schedule, a consistent caregiver, and a goodbye that is the same length and shape every day. None of it is a shortcut, but together they remove the variables that are actually within your control.
Part of our guide to Starting daycare.