I have my V85TT in for its 1st 900 mile service a week on Saturday, if I leave it till then, by the time I’ve ridden to dealer, it’ll have bang on 900 miles on clock, would it matter if I went out this weekend, and took it up by 200 miles or so, so I end up with say 1150 mile on clock?
A 100 miles or so wouldn’t matter imho. I made the mistake of putting the two of ours in just before the service light came on, result was we had to put up with the light being on until the 6000 mile service. The lack of ability to reset the service light is a major pita! All about getting more money for the dealers !
Thank you 
they can reset the light easily in a minute or two and most dealers dont even charge for that. they just lift the seat and plug the PADS device in and press a button.
I think its a common occurence, as lead times booking with Dealers is pretty long.
By the time you attend for the date given, your mileage will undoubtedly have increased.
When i had my last bike ran over a few hundred miles each time and had no issues with warrantys etc.
I think as long as its reasonable most dealerships will take a practical approach.