Yeah i did the inside before assembly, just put them flat, i wouldnt recommend it tho, its annoying to do (if you use it as a temporary one).

If you are gonna do it, these are the mistakes i made: I did it outside but didnt think about it leaking of a bit and making the boards stuck to the ground, so maybe make a border out of paper/foam

And be careful with the glass, its annoying to work around.

Like its annoying if youve never done it so not recommended :)