Loss of gravity is not linear. It is fastest at first. For really big beers it may take month or two. Also, it depends on temperature, initial availability of nutrients and oxygen, pitch size and so on.
For 1.065 OG ≈ 16°Blg, I would left it alone for two weeks and don't even bother measuring anything during that time. 1.030 OG ≈ 7.5°Blg is too far from finished to think about dry hopping.
After two weeks I would expect it to be between 1.01 and 1.02 (3 to 5°Blg). Dry hopping gives best results if hops spend between 4 days and a week in brew. Sources vary. My personal experience tends to be about 5 days, but feel free to experiment, and remember that anything in this range will be OK. It's common way to bottle when gravity do not change for three consecutive days. But this happens, more often than not, in the middle of the week. So when you know it's safe to bottle, just schedule it in a way that would give you 4 or 5 (or more if you wish) days. Dry hop then, and bottle during weekend. One more week in fermentation bucket would not hurt your beer in any way.
As for a way to add them - soaking makes little sense. Unless it's in boiling water, then it may help to kill germs. Personally I always threw hop pellets dry straight into fermenter and it never caused any issues. But can't say the same for other hops. And of course it is in no way proof that it's safe for you. I wouldn't bother, but that's your brew. If you soak it in boiling water, use as little water as feasible and then add both hops and water used.