Should be around 10 minutes (pending natural lag in the livestream etc.) There's usually a really big vent just prior to engine firing from the TEL.
Launch weather forecast, 80% GO:
Launch day probability of violating launch weather constraints: 20%
Primary concern(s): Cumulus and Anvil Cloud Rules
Delay day probability of violating launch weather constraints: 20%
Primary concern(s): Cumulus and Anvil Cloud Rules, Liftoff Winds
L-2 Launch Weather Forecast. Still 80% go for launch day.
Much better mission patch version. Extracted from PDF file as separate object.
Tweeted, but when I went to RT, it said action unavailable and that's because they deleted it.....sorry, which I could have grabbed the pics, but at least screenshot the deleted tweet.
Oh, they deleted it because they typoed. Proton 9

Anyway, they haven't tweeted the correction.....we get the message and the milestone.