either/or. if you're going to do both eventually, go for whichever. blower is easier to put on first, just don't overboost and make sure you're safe. HCI is a lot more work initially, but if you do it later on you'll just be putting it off until then.
As far as labor goes, if you're doing it yourself and don't mind redoing some things then flip a coin. If you want to do as little as possible over time, do HCI now and blower later. Otherwise you'll basically put the blower on twice if you do it now and HCI later; though it never hurts to get better at stripping/installing it over and over again. I can do it in about 1/10th the time it took me originally

If you go with an A-trim/5-6lbs. boost setup you can get away with a pretty safe setup w/o a full custom tune + chip. If you go higher you're going to be pushing it as far as not tuning, and would be much better off getting one. Point being, it's not a great idea to get Tune A for now and Tune B for soon after. Unless you don't care about a few hundred bucks, then it's negligible. Or you can run an FMU if you're into those. I personally wouldn't consider it but I know tons who have without problems.
You can go back and forth all day with it. Overall you'll be happy with either choice, and the addition of the remaining upgrade later down the road will make the car another animal.
Truth be told for the longest time I wished I kept my underdriven A-trim + stock head/cam setup (had an aftermarket intake on already). I'm happy now but that setup was a blast. Put down 300/330 at the rear with it.
...it's much more fun now that everything's worked out though
