if youre going to be wanting both eventually...do them at the same time instead..that will cut down on a lot of labor costs if youre going to have a shop do it.
If you plan on getting both for certain, and you can't afford them both right now, go with the heads first. Cams and even valve springs can be installed later on without having to tear the entire top end of the engine down again....but heads can't!
If your going to supercharge it one day, don't bother with heads or cams unless you are going to build the bottom end of the motor to support alot more power.
Blower + heads/cams on a stock bottom end is way more than the engine can handle. The blower will get you there fine by itself.
But for some....it could be a loooong time between going heads/cams to a blower and short block upgrade. I know guys who talked about if for years and in the end ended up selling there cars before they could actually afford it.
Besides....just because blower + heads + cams give you the potential to make more than enough power to grenade the stock engine, doesn't mean you have to push it that hard. As a matter of fact, some may increase the longevity of their stock short blocks after the head and cam swap, since they won't have to push the envelope quite so far to see their desired power levels once the blower is bolted on.
lots of money, but it is WELL worth having a car with lots of power and that can handle it properly and shows these weed eaters at the strip what a real car is haha