Bearing in mind:
1) you have a very regular cycle - 25/26 days long, always ovulate 14 days before next period arrives (aberrations are rare - maybe once a year the cycle will be 27 days long instead).
2) your sperm donor will be in a different state
A) prebook flights for the day before, day of and day after predicted ovulation or
B) wait until you have a positive OPK and then book a flight asap?