Among those braving the warm sunshine and sweltering air were Bolt's parents, on board for the first appearance of the world record holder later on Saturday in the first round of the 100 metres.
The double Olympic champion, out to reclaim the title after being disqualified for a false start in the final two years ago, makes his first appearance at 5.15 p.m. British time ahead of Sunday night's final (6.15 p.m. British time).
The first medals of the championship will be decided later on Saturday in the women's marathon and the early stadium action centred on the decathlon and various qualifying rounds.
Organisers have claimed to have sold 80 percent of tickets for the August 10-18 event but there were acres of yellow, red and orange seats vacant on Saturday, producing a multi-coloured backdrop to the vivid blue track and artificial green grass infield.
American Olympic champion and world record holder Ashton Eaton set the early pace in the decathlon with a 10.32-seconds 100 metres and 7.32 metre long jump for a two-event tally of 2003 points.
Germany's Michael Schrader was second on 1944 with another American, Gunnar Nixon, third on 1907 after a personal best long jump of 7.80.
There was a surprise in women's discus as China's Siyu Gu, whose 67.86 metres makes her second in the world this year behind dominant Croatian Sandra Perkovic, had a miserable morning with three fouls and failed to reach Sunday's final.
Ukrainian Natalia Semenova will not forget the event in a hurry either after being cracked in the face by Zaneta Glanc during the Pole's discus-swinging warm-up routine.
European bronze medallist Semenova, who had been sitting on a bench minding her own business, received treatment for a deep gash on the bridge of her nose and was able to continue but she managed only one legal throw and failed to qualify.
Ethiopian Mohammed Aman, the only man to have beaten absent world record holder David Rudisha over 800m in the last three years, underlined his status as favourite to take the two-lap gold as he produced the fastest time of the morning heats, one minute, 44.93 seconds.
His compatriot Ibrahim Jeilan will be in action in the only track final later on Saturday when he seeks to retain the 10,000m title.
However, Briton Mo Farah, who he memorably caught on the line for that title in Daegu, starts as strong favourite having gone on to complete the 10,000/5,000m double at last year's London Olympics.
(Editing by Justin Palmer)
