Re-impregnating tent & footprint best?

[irrelevant]

So after some 6 years it seems my tent & footprint might do well receiving a dose of re-impregnation. I got 2 cans of Imprenex for this tent, and its footprint (see schematic view for sz).

https://www.outdoorsupply.co.uk/tent-va ... 200-cactus

I was planning to put it up and spray it outdoors, but a friend said he'd found that not to be very efficient, or economic (getting the spray everywhere else, on himself, etc).

He recommended I instead do it indoors somewhere (I'm thinking our attic), and to pay extra attention to the seams.

Does anyone have any recs on how to best do this? Also wondering for how long the gear then would need to dry enough, before packing it back up.

Thanks in advance.