The first session for the event, which includes the Classic TT and Manx Grand Prix, opened with a speed-controlled lap for newcomers on the TT course.
Saiger's opening lap of 117.18mph on his Greenall Racing Kawasaki was the quickest of the evening session.
The second practice session will be held on Tuesday.
Monday's scheduled second qualifying session has been cancelled due to rain and low-lying mist on the Mountain.
Double Manx Grand Prix race winner Andrew Dudgeon was second fastest on the night with 115.39mph, with Australian David Johnson and Lee Johnston both averaging more than 114mph.
Fifteen-time TT winner Michael Dunlop missed the session to compete in the Ulster Rally, whilst Kiwi Bruce Anstey topped the Lightweight timesheets.
Thirty-eight Manx Grand Prix newcomers completed their compulsory speed-controlled lap under the guidance of experienced TT racers.
Santon-based Michael Evans topped the qualifying board on his Senior Martin Bullock Motorsport Suzuki with 114.518mph.
Meanwhile, Brendan Fargher (114.236) Tom Robinson (113.988) and Glenn Harrison (113.828) all posted competitive times on their 600 machines.
Six newcomers slid off on their opening laps with Lief Williams and David McConnachy taken by ambulance to Noble's for check-ups.
All have been reported as okay.

Emergency services were called to the line near Stanford-le-Hope, Essex, at about 21:30 GMT on Monday.
A tow truck had to be called to remove the car, which was stuck on the track. No one was trapped or badly hurt.
The 18-year-old driver was arrested at the scene on suspicion of theft of a motor vehicle, driving without insurance and careless driving.
Train operator c2c apologised for delays to passengers.
It said services were disrupted for about three hours while the car was removed and Network Rail engineers examined the track and repaired the fence.
Austrian Horst Saiger has gone quickest in the opening practice session for the 2017 Festival of Motorcycling on Saturday.
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A motorist crashed through a fence and onto a train track, causing several hours of delays for passengers.