Man, I applaud you if you wanna go for it just to know that you did it. It sounds like you don't need to make back-up arrangements because the back-up would be your mom's car. So why not try it the first day?
Personally, when I was commuting roundtrip 6-8 miles a day, I could go out and do a 50-mile bike ride for fun on the weekend. 25 miles out, stop an hour to have lunch at a diner, 25 miles back. But that was, like, my thing that I did that day, I wouldn't have wanted to work a full day on top of it. When I moved closer to work and walked instead of biking, I tried to go on a touring trip and quit after the first 40 miles. So to me, your lack of base mileage is what dooms the plan. But I'm not naturally athletic and you may be.