reinstall filon siding

Personally, I would hang the luan first and then glue the filon to it.

The reason I ask is ,if I hang the lauan first then roll contact cement for filon adhesion, what will my work time be? Immediate stick,no room for error? I cannot find any info about this subject on the web.

If you use standard contact cement, like Weldbond, the work time is usually not an issue. Once both parts are dry to the touch, they are ready to be bonded. There is no "work time" after bonding. You have to be right on the money. I don't think I would use this to glue my camper back together. I have used construction adhesives to replace lauan beneath the Fiberglas on mine with, so far, decent results. However, clamping can be a very creative exercise.
Good luck.

Did a search for Filon on google. First site has info on Filon install using Stabond contact cement. Might be of help to you.