I agree that it isn't going to matter in the long run, but disagree with GdD as to why.
Cars don't have an octane sensor. What they have is a knock sensor. When octane is too low and things go bump in the night (ping or knock), the knock sensor picks this up and pulls ignition timing to make the ignition cycle occur later in the revolution. This has the unfortunate side effect of reducing power. The car pulls timing so the low octane fuel won't damage the engine. As long as you don't push your car (think easy driving), it shouldn't have an issue.
Luckily, there is a way to fix your issue without having to drive it very much. There are octane booster additives which you can use right away which will solve your issue. Drop in a can/bottle and you should be good to go with no worries.