Can I have fire or conduct curing fires in the oven before I attach the ceramic fiber blanket or apply the stucco / brick finish

It would be better if you didn’t…

When you start a fire, it releases soot and smoke. While most of that soot and smoke goes out of chimney, some of it will escape out the front of the oven and adhere to the Firebrick / Concrete / Castable Refractory. Or to the cinderblock and concrete panels if you are building the BrickWood Box.

You need a CLEAN (soot and smoke free) surface when attaching your veneer to the stucco shell (over the ceramic fiber blanket) if you are building a BrickWood Oven or to the cinderblock / concrete panels if you are building the BrickWood Box.

Long answer short: Don’t start any fires (curing or testing) fires until after the oven is completely finished and preferably after the oven is sealed with Organic Masonry Sealer.