I don't see anything official about when it is. Hard to start the Countdown to Spring 2026 thread without it! That thread always brings me a mid-winter smile.
Good to get the jump though! It's probably February 10 or 11th, and it always seems to be a little wobbly depending on whether you count the first work-out or them actually showing up the day before.
That is a tricky question but the consensus I get here is to count the first pitcher and catcher workout rather than the report, fill out paperwork and take physicals stuff the day before.