Roads around the Mountain Course are due to close at 5pm on Saturday , until no later than 9pm.
MGP and Classic TT newcomers will go out first, followed by Senior, Junior and Supertwin MGP competitors.
Last out will be Classic TT, Lightweight and all newcomers.
It's the start of two weeks which will see if all the planning and changes to the format will pay off.
The major part of the shake-up is the new Classic TT, which has attracted entries from many TT regulars and teams.
It will be held over the August bank holiday weekend.
The likes of John McGuinness, the Dunlops, Guy Martin and local favourite Conor Cummins will tackle the Mountain Course on a dazzling array of machinery from the '70s, '80s and '90s.
The Manx Grand Prix, shorn of the classic races, will take place on the Wednesday and Friday of race week.
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