Maybe the very first time you try mileage it might make some sense but once you've done it once, it seems over-cautious to go up that slowly.
But if you are young, healthy and/or just not very injury prone, you might as well try going right to the 70s. Or maybe try the 60s next week and the 70s the week after. If you can't handle it, back off. Just pay very close attention to aches and pains that form.
More important though: Why do you feel the need to get to the low 70s so quickly? Is this some requirement?