I sent the form to my employer three days ago and haven't heard back from them yet. I don't mind waiting but I don't know anything about the process and how long it typically takes.
Depends on the level but generally speaking you get the interim in as little as a few days (usually a week). The final takes about a month or two depending on how many places the investigator has to reach. Most people who fail to get the interim ends up getting the final. Very rarely people pass the interim but fail the final.
Generally speaking a company will not wait for the final if someone fails the interim. In the military you'd simply get assigned to a job that doesn't require a clearance until your final comes.
Edit: As an aside note, SF86 is sent to the FBI, not your employer. Nobody can initiate a SF86 by him/herself without some sort of requirement. So if you didn't fill out an online form from the government, then you probably ran into some sort of scam. You should have also submitted a finger print card.