Wait for the calipers to arrived, then fit it with it bending the stay.
This is a very good site with example of fitting with disc calipers;
http://www.cyclingabout.com/mudguards-and-fenders-for-bicycle-touring/
Cheers Ed, sorry to clarify I meant the rim brake calipers. Where the mudguards will have to attach to the crown of the fork and the brake bridge on the seat stays.
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Wait for the calipers to arrived, then fit it with it bending the stay.
This is a very good site with example of fitting with disc calipers;
http://www.cyclingabout.com/mudguards-and-fenders-for-bicycle-touring/