Originally Posted by
mtkeller
Wherever you read that was lying. The best time is about three days out, but
outside of that, there's little rhyme or reason to when space opens up. Often see it at 10 months or even closer in for the initial offering of low space.
To avoid issues, book a dummy return when you book the outbound and then just make your free change whenever you see what you want for the return. They cannot merge them if you book them separately, and DL's systems are notorious for failing to recognize a change from a one-way at 100K to a r/t at 100K and you might get a random amount. If you're replacing the return, it should be straightforward.
Thanks. Good to know. Will look for a low dummy return and then change. If I can't find any low mileage flights will just keep looking. The return is from a different city but that shouldn't effect ability to change. Any chance the change could impact the mileage requirements on the front end flight - could it change to a mid or high mileage even though it was booked initially at low mileage?