It most certainly has been established when the alert occurred to the nearest few minutes. There is the evidence of many people who were in or around the club just before it all kicked off. The resort was quiet at 10pm and a scene of great activity at 10.05pm, does that give you as clue?
And as the Smiths sighting was at 10pm, they saw the mystery man even before it was discovered that Madeleine had gone.
Exactly. Also if that was Gerry the Smiths saw, then he hadn't even got to his destination yet - wherever that was. He still had to get there, then bury/hide the body, and then get back to the apartment and change his clothes- all in about 5 minutes! A physical impossibility - obviously.
Not much of a plan is it when the alarm is raised
before the 'culprit' has even arrived back to establish his alilbi. No-one in their right mind would have that as part of a 'plan'.
The whole idea that it was Gerry the Smiths saw is ludicrous straw-clutching. imo.