[losthelm]

A lot of ovens and kilns will spike temps as they heatup.
Much like older thermostats, the temp may actually be a bit warmer befor the element cycles depending on the placement of the thermo coupler, heating elemtents and openings you can also have spots that are warmer or colder.

This is why your cookies may need to be rotated to get an even color when baking, the top rack cooks faster, why the cook times vary a little between the first tray and the last.
And convection ovens are faster than traditional ovens.
You also have thermal transfer that can affect cooking times between aluminum pans and glass pans.
Not that this has anything to do with glass work just an illustration of what might be contributeing to the issues of your mini annealer.