He should go early with a tie. How should a lawyer show up to an important court case – early without a tie, or late with one?
One of the premier mechanchim of our generation put it this way –
“When it comes to a Rebbe’s timeliness, the rule is:
Better never than late!”
I think it is obvious that a Rebbe must project the respect he has for his students and his position, certainly no less so than any other professional. You need to be on time. You need a tie.