The answer is yes. Ideally a tiny puff of gas will give it enough pressure to hold the orings and seals in place, but even a full charge is better than non at all, I find.
Once you have any liquid in the mag, then you can have it from a drop all the way to full charge and you will have the same pressure. The only problem would occur if the mags were exposed to high heat in storage. (Don't store them in the attic; or the oven)