We have a guy in our league that for the last month has been practicing on the pair he is scheduled to bowl on just before league starts, I thought i had heard that you aren't supposed to be able to do that.
Brought it to the league secretary and he didn't know if it was a rule or not, so this week I asked the person running the counter, and they didn't know either.
It isn't a huge deal, but it seems to me he gets an advantage by bowling on the pair leading up to league that night.

Big deal yes or no?

Thanks for your input

If there's no league rule against it, it's USBC legal.  When you bowl his team, if you want the advantage, get there before he does and bowl on the pair yourself.    --  JohnP

I have thought about getting there earlier and trying that, last year it wasn't an issue as we had a company league that bowled before ours, but like so many leagues that one folded.

Other posters are correct.  It is NOT a USBC rule, but some leagues have a rule preventing it.  It is not an issue with my house, because management will not allow anyone to bowl on the pairs that have been oiled for leagues.

You can bowl on the pair of lanes before they run the league shot but after the shot is placed he isnt allowed....

Happens every week in my league.  One of the participants doing this is the league secretary.   Some have thought to take a plastic ball and spray all over the place on the secretaries lane or lanes and screw up the shot for everyone on that pair to prove a point.  But then, that's also giving them the opportunity to do average control.

Our house waits to run the oil about 30-45 minutes before league begins.  You can get there early and practice, but once the lanes are oiled nobody is allowed to bowl until leagues starts.  Again, that is the bowling center rule, not the league.