Just for fun --- I wanted to see how long it took for my compressor to kick on from a full tank.... so I drained the water valve (on the bottom of the tank) until the compressor kicked on. When it stopped --- I started my timing.
My bead blaster at 100 psi --- took 1:27.46 --- one minute 27 seconds until the compressor kicked on.
I set my regulator to run at 90psi with the tool operating... and I used My Snap on cut off tool which is rated at 2.7 CFM @ 90psi in freewheel mode - which is how I tested it -- took 1:17 -- that's doing NO WORK -- just freewheeling.... 1 minute 17 seconds.
JUST FOR FUN --- I ran the exact same type of tool --- but this time it was my NAPA Evercrap (ever craft) air cut off.... the cheaper tool took 51.76 seconds before the compressor kicked on -- so the cheaper tool used a lot more air. I will also tell you that the Evercrap tool is no where near as torquey (powerful) as the Snap On that took less air.
My compressor is a Champion Advantage VR5-8 --- 5 hp 220V 80 gallon storage tank.... that delivers 19.1 CFM @ 125 psi
http://www.compressors-champion.com/vr58.cfm
Barely over ONE STINKY MINUTE before it kicked in.... and this is an extremely good $2800 (expensive) compressor. ONE STINK MINUTE.