I'd go ahead and slowly add the salt. my method is to add 1/4 teaspoon per gallon every 2-3 hours until I reach a level of 2 teaspoon per gallon total. The heat has two effects the first of which does the most to help your fish. 1st effect is that elevated temps speed up the life cycle of ich. since it can only hurt your fish while it is on them, and it cannot be killed while on your fish the higher the temp the sooner you can help your fish. it will hatch off of your fish sooner in warm water. with this in mind, 78 is better than 76 and 80 is better than 78 so on and so forth.
2nd effect at 86* F Ich cannot survive therefore getting the temp up to that point is most desireable. however ich cannot survive the salt either way so if you can only achieve 82* but the salt is there you will kill the ich. it is better to give it the double whammy of salt + 86 * but salt plus *2* will work.
The big important fact in all of this is that ICH can only be killed during the free swimming stage while it is out looking for a host. the stage when it is on your fish is stage one, feeding stage (continuos cycle of three stages so one is an arbitrary number), then it goes into the substrate and multiplies (stage two) then hatches out ( multiplied in numbers) and goes freeswimming (Stage three) to find your fish again and feed (back to stage one). if the temp is high and the salt is in the water it dies as soon as it hatches into freeswimmers. The sooner you can raise the temp and get the salt in place the faster the ich will die, but be sure to treat for at least 1 full week after all signs of ich are gone from your fish. many people stop treatment as soon as the fish look good, and by the time the ich hatches, there is nothing in the tank to kill them and they go on reproducing and living in the tank. if your fish are healthy the may only attach and grow on the gills, and thus go unnoticed until something stresses your fish again and boom you have a big ich outbreak. This is the source of the myth that ICH is always n the tank and can't be irradicated. Let me know if you have any other questons.
HTH
Dave