I wouldn't feed any at this point, should of stopped feeding about 2 weeks ago...if anything just plain water, but with just a couple days...don't water. let the medium dry up. With your soil dry your plant will use all moisture in itself.
it will create more trichomes to protect itself, plus your buds will be partially dry when harvest.
I have done the cold water flush. not ice cold, but cold. At two days prolly not worth it.
My pre harvest regiment:
At about 2 weeks before harvest stop feeding.
Do a good plain water flush... I use cold cold water. ice will help get it colder, but you don't want it too cold to ware it may do damage to roots, just shock them.
I have a very aerated medium. A lot of perlite and holes in pot, so my drainage is fast.
So I was able to flush again a week later.
I also lower temps in my grow room.
This next step, not recommended if your humidity it too high.
I had a clean room and a way to control my air and humidity.
so I also misted my plants with cold water. to simulate a late fall rainy day. misted right before lights on and also in middle of light cycle. (raised my lights as far as I could) real good air circulation. every day.
Mostly I didn't mist the buds directly, didn't want them to get moldy.
To be sure tho I would shake them to fling off water, they seemed to react to that imo.
The last 2-3 days I would leave them in total darkness before chopping.
If you have a lot of plants to deal with, just don't do the misting... prolly best to leave it out, so as not to cause problems for you. most people will say "do not spray or mist" your buds that late in flower, I agree. but I have been able to do it successfully.
There will be some people say none of this works, but it does for me.
Good luck