whatever you decide, just know this. you have to be at your current position for atleast 6 months before applying for a different position (such as one with more hours). so, if you take this position now, you won't be eligible for the 20-30 hour position in oct. you could always move up in hours later down the road, like i've been doing.
if you take the lancome position, there's no guarantee that you'll be able to transfer when that position comes along. i think if you work at another counter, you have to work there for a certain period of time as well before tranferring to a different counter, but i'm not 100% on that one.
and if you wait til oct, they may find someone else to take the spot.
if i were you, i'd take the 8 hours now. that way you're in, and can work your way up, instead of waiting for a spot that you might not get. and with being unemployed with the way the economy is, it kinda makes finding another job right now tough.
you also have to condsider the fact that classes haven't started yet and you don't have all the arrangements made yet. you didn't mention how far away classes are, but with only 8 hours a week, it sure makes it easier to work and take classes at the same time.
good luck with whatever you decide to do.