When I replaced the speedometer on my '07 Heritage I had to tell them what milage to put on it. It took 2 weeks to get it so I estimated how much I would ride and added it to the existing mileage.

 

Did the same thing when I ordered the HD combo speedo / tach for my 03 Heritage. Took 4 weeks to get so I guessimated where the bike would be when the unit arrived. It ended up within a few hundred miles. That was at 1000 miles. Now the bike has 31,000 on it and in the big scheme of things that couple of hundred don't matter.

There is probably enough error in the system to cover it. HD odo's are notoriously inaccurate. The one on my Ultra reads high. About 50 miles per thousand.

 

50/1000 is right at the upper limit of accuracy required by government regulations, as I recall them. This is no doubt in part due to decreasing tire diameter. Maybe they need to go to greater technology to actually scan the ground moving under the bike, like what's done with an optical mouse for our computers...