How long is my form taking?
USCIS publishes a range per form and per office. Both matter — the same form can differ by months depending on where it is being handled.
Forms decided centrally, at the National Benefits Center or Service Center Operations. Here the category of work is what changes the answer, not the office.
I-600 — Petition to Classify Orphan as an Immediate Relative
27 to 33.5 months (2.3 to 2.8 years)
National Benefits Center
Estimated median
24.7 months
The published range is the slow tail, not the middle: USCIS's low figure is where about 80% of cases have finished and the high figure about 93%. So half of cases finish sooner than 24.7 months — three in four by 26.7, nine in ten by 32.9. An estimate from those two published anchors, not a figure USCIS publishes.
Ranges are as published by USCIS: the low figure is where about 80% of cases have finished and the high figure about 93%. Confirm on Check on USCIS's processing times page.