How long does it take?

Let's say you're in a car, some distance away from your home.  You change your speed so that once you're x miles away, you travel at x mph.  How long will it take to get home, approximately?  Consider two specific cases:

1) You change your speed continiously, so that at, say, 7.5 miles away, you're traveling at 7.5 miles per hour.

2) You drop your speed by one mile an hour for every mile traveled.  That is, at 7 miles away, you go to 7 mph, holding that speed for a mile, then going down to 6 mph at a distance of 6 miles away.

Does it matter how far away you are when you start?

>>1
The question is all over the place
You don't state if your driving to home, or away from it.
On the considerations you state you might be driving 7.5 miles an hour at 7.5 miles away , but in 2 you say your dropping speed by 1 mph for every one mile travelled.