My understanding of the IDEAL time to pair is approx 90 days before the 1st race.
If flying natural for the distance then you need to adjust the time to get the nest conditions that you want the birds to fly home to.
ie, driving, sitting,chipping, or with young in the bowl.
Unless you want the young birds from your Distance birds then I would say leave em alone for now and pair them nearer to the race.
If you intend racing the young off your distance birds I would of suggested breeding as early as practical, young birds onto darkness system and then split the old birds and re-pair again nearer to the race
mO.