Their predominant stances favors the stronger counter puncher which is Conor. Both their lead hands with be gauging the distance which will play a huge role in the fight. Floyd is used to boxers who stand closer to him than Conor will.
Conor has that open karate stance and seems to bait punchers by leaning forward at a medium distance but then takes one step back as they come forward while throwing that left hook at full follow through distance. Precision and timing along with power and a bit of bullying will definitely spook Mayweather as had in the past.
All pressure is on Mayweather as well, both of them saying they will both come forward and KO each other may be all talk but the Irishman has the touch of death in that left hand. If Conor wins, it's before the 6th round, if not Mayweather outpoints a frustrated Mcgregor to a UD. McGregor never really had anything to lose but everything to gain anyways. The bigger the spotlight, the longer those multi-million dollar checks keep coming. He will come back to the UFC win or lose and then barter for an ownership stake in the company. I'm pulling hard for the guy, he takes big risks and always puts on a good show.
I'd say be ready for 11:30 to midnight, probably closer to midnight since that's right around 9pm Vegas time.