Mongolia-Russia crossing at Naushki [duplicate]

In a few weeks I will be using train 305 to go from Mongolia to Irkutsk. This train leaves on a Tuesday and arrives at Irkutsk on Wednesday. According to Russian Railways, this train arrives the border point at Naushki at 23:55, still Tuesday, and stays there a couple of hours.

The thing is, my visa is valid from Wednesday. I know that technically if I really arrive at 23:55 my visa will not yet be valid, but by the time the guards take my passport it would probably be Wednesday already.

Maybe a better question would be if guards will stamp the visa with the Tuesday date or Wednesday, since it will in fact be Wednesday. But only people that have traveled on that particular train will know.

Anyone that has traveled on that train or in a similar situation could tell me what chances I have to be taken off the train?

EDIT:
This is the timetable from Russian Railways. Times until Sukhbaatar are local. From Naushki times are Moscow time (add 5h for local).