One year ago Okoro was close to quitting the sport for good after controversially failing to earn selection individually for the 800m for the London 2012 Olympics.
However fast forward to the present and the outlook looks much rosier as she finished her heat second in a season's best time of 1:59.43minutes to qualify for the semi-finals.
And the 28-year-old knows exactly where the praise lies for her comfortable opening outing at Moscow's Luzhniki Stadium, at the feet of coach Gray.
And she insists Gray's big-time experience that saw him claim 800m bronze at the Barcelona 1992 Olympic Games is already proving invaluable in Moscow.
"I'm very pleased with how my heat went," she said. "It was a season's best and I'm just happy to have executed my race the way I did.
"It was a tough draw and I thought 'I know how these girls run' so I just really wanted to relax and go through the motions and use my speed at the end and try to stay really calm.
"Johnny's a front runner and that's what works best for us when we're trying to go get those fast times. This is a championships though so he's definitely been beasting me and making me strong.
"Of the little stuff we've done together I'm really pleased with how it's going, but mostly he's teaching me how to run the race well."
Okoro will be joined in the 800m semi-finals by fellow Brit Laura Muir, who celebrated her maiden World Championship outing by finishing her heat third in 2:00.80.
However 18-year-old Jessica Judd will not join them as she saw her own World Championship bow end prematurely as she could only manage 2:01.48 to cross the line fifth in her heat.
"I've come a long way this season," said Judd. "It's been my best year so far and it would have been a dream if I could have made it into the final, or at least a semi-final.
"Going out in the heat wasn't on my agenda at all, that's why I am so disappointed. I know I could be a finalist, I can run so much quicker, I think I'm in 1:58 shape so to run over two minutes is just a disaster in my opinion."
There was more disappointment for Anyika Onuora in the 200m as she finished fourth in her heat in 23.36 seconds, missing out on a place in the semi-finals.
However European under-23 champion Jodie Williams marked her world bow in style as she qualified for the semi-finals as one of the fastest losers having clocked 23.00.
"I feel pretty good, 23.00 is the fastest I've ever run in a heat and I've never come out and run that fast in the first round, so I'm pleased with my performance," said Williams.
"I get better through the rounds so hopefully I can get a bit quicker. These girls are running so fast, it's just an honour to be here really.
"In the next round I'm going to run as fast as I can. It would be great to come here and run a personal best.
"I always like to come to championships and run the best that I can and I feel like I'm in personal best form. Hopefully in the next round that's all I can ask for."