A schedule change is not going to allow you to move the flight by a month and depart from a different airport. What it would do is secure a refund of that segment on a half-round-trip basis, without penalty.

OP: You booked BE to save money; it backfired. I don’t fault you for this: I wish I could book BE, but UA’s restrictions on the product are far too Draconian. That said, your numbers feel off: it feels as if you’re being charged for the change as if you were buying a brand new ticket (and paying no-advanced-purchase prices) instead of changing an existing one. I agree with DawgmanOH here (and given the football teams I cheer for, that’s saying something . See what it costs to make the change after you arrive. Unless the flight that you’re booked on happens to be nearly sold out — in which case, your alternative plan wouldn’t work either — I suspect the price to be much more palatable.