You're looking for a specific answer and there isn't any.
All fermentations are dfferent. They are based upon several factors such as yeast count, amount of malt sugar they have to eat, temperature of the wort at pitching time and fermentation temperature, etc.
Some of the numbers you should have paid attention to I can bet you glanced over...what's the attenuation of the yeast? What, you say??? Check the yeast packaging. On it it'll state the attenuation. If it's not there check a cross reference chart or the manufactureres website for the info. I use 75%.
Removing the cover for a peek will not infect the brew unless you took a dump, wiped with your hands, didn't wash up, and got crap inside the bucket...an extreme example, I hope...
The only true way of knowing your brew is done fermenting is by using a hydrometer. If your OG has dropped within the range of the attenuation numbers then it's done fermenting...thus your FG.
The bubbles, for lack of a better term, are for show. They give you something to look at while it's fermenting.
When they begin to slow down then you can take your readings.
Many experienced brewers will not even look into the primary until day 10 or so. Then only to take a gravity reading and do the calculations. If the FG is not within the proper range the cover goes back on.
Learn more patience. The beer will taste better in the end.