Scoring: 3rd out timing play

[Cavman]

Question on 3rd out timing play.

Runner on 3rd base and 2nd base in LL with 2 outs. Grounder to 3rd baseman with both runners on bases advancing. 3rd baseman tags runner from 2nd coming to him no hesitation.

My question is, does the run count from third? Does it count if the runner from third crosses home before the tag or the batter/runner tags first before the tag.

Thanks