I do think FinallyFlying makes a valid point - Although "level by . . . ." means exactly that I can't think of a colleague who would mind, or complain, if you levelled 1 or 2 miles early!!
I know it's slightly non-standard (and therefore must be frowned upon!) but i have sometimes used "be level at or before . . . . "
It does appear sometimes that, as said before
What happens too often is a VNAV descent that the computer on board initiates as late as possible before the waypoint. This give ATC the heebyjeebys because it looks like you've forgotten to descend or will be too high.
An aircraft descends at 3000fpm or more which will make the restriction with about 100yds to spare, then, of course reduces its descent rate, as it needs to level off, and misses the restriction by about 600ft or more!!