Here are some times I found for various calibers and manufacturers, using the 0.625" diameter water-cooled coil. I determined the times both with 750-degree Tempilaq, and by watching for a very brief glow from the brass with the lights turned out.
.223
LC, FC, WCC - 1.0 seconds
WMA, PMC, Wolf - 1.1 seconds
CBC - 1.3 seconds
6.5 Creedmoor
Starline - 1.6 seconds
Sellier & Bellot - 1.8 seconds
.308
WCC, WMA, MKE, FC - 1.8 seconds
LC, PMC, PPU, CBC, Aguila - 1.9 seconds
MEN, IMI - 2.0 seconds
Lapua - 2.1 seconds