I started my first ever batch on Saturday (a free pale ale that came with my equipment) and now on Monday I still have not seen any bubbles in the air lock. I kinda panicked and opened the lid of my plastic fermenter to look and I THINK it smells yeasty(similar to a beer smell?) and some gunk on top. I'm just worried it's not fermenting wether from the cheap dry yeast that I didn't rehydrate or maybe I didn't aerate enough to begin with? Any suggestions on what to do? Should I take a hydrometer reading?