CC
Depends on strokes of the fokes; when you're doing 2000ft per minute, 1 mintues warning is more than acceptable, I'd have thought...
But if you were doing 500ft and called 2500 above, that's excessive...
I've had QFA 767's assigned FL290, leaving FL350 reporting approaching. I hate that... Or worse, 'expect lower in 15 miles due crossing xxx', 7 miles later 'approaching FLxxx'...
The airpace structure going into SY; has sector (vertical) boundaries in a few places. Abeam CB FL 285; 110 SY FL245; 90 SY FL205. So we can assign without coordination FL290 initially, FL250 and FL210 and A100 at those steps. Often this is tight with QF762, QF332 profiles; so we often get the approaching call; but can't give for another 30 seconds or so... Or coord, which may take 30 seconds to complete... This is often the major generator of 'in with a ground station, say again'; I'm doing coord to get you lower.
Bottle of Rum