I have been soaking 2 corned beef briskets in preparation for pastami making. I won't be able to smoke them until Friday. Do you see a problem with putting on the pastrami rub, wrapping them tight and then refrigerating for 4 days?
Just my opinion but I see no problem with that. Just tucked away 5 pounds of thin sliced vac sealed pastrami in the freezer. I too used corned beef briskets but I don't soak mine. I simply rinse them but several folks do soak them. I rather like the taste without soaking. My pastrami was rubbed on Friday and smoked on Sunday so that's two days. Don't know why two additional days would hurt. Go for it!
I too never soak mine but, I make all of my own corned beef from scratch. If you buy store bought then it probably varies a lot from brand to brand. I'd think that four days wrapped with the pepper corns and coriander might be a tad too much for my taste. I put the spices on and then smoke straight away.
The brisket is already cured and i have had mine in the fridge for 3 1/2 days before smoking.
you will notice that it begins to leach liquid after a couple days so you may want to flip it daily
and put it on a sheet pan of some type to avoid leaking onto the shelf in the fridge.
My view - they're okay as cured but don't put the rub on at this point. Rub when ready proceed. If there is any question on timing you can freeze it in the cured state and then proceed at later time.