In reality, admitted the Commonwealth champion, nothing can be taken for granted as places at Glasgow 2014 are chased and cemented in the months ahead.
The City of Glasgow swimmer hauled himself from sixth to first, holding off rising star Roberto Pavoni to secure the 400 metres freestyle title at the Commonwealth Pool in his first outing of the winter. It was a consolation, of sorts, on an evening when the 25-year-old watched teenage prospect Duncan Scott spirit away two of his Scottish junior records.
Such competition provides a healthy incentive. It, he acknowledged, was just a foretaste of the numerous challenges to come as rivals at home and abroad duly raise their game. This was just an initial trial. "The morning was a real shock to the system," Renwick declared. "I've been training for four months solid and that was my first race. I felt absolutely terrible.
"I slept afterwards for three hours and I'm a lot happier after the final. It was so much better than the morning. But it just shows that it will be really tough all this weekend. If I can stay just ahead of them, I'll be happy."
Kathryn Johnston, of Edinburgh University, was only other homespun winner, in the 100m breaststroke. However Ross Murdoch smashed his Scottish record in coming second in the 50m in 27.06 while Richard Schafers equalled the Scottish 50m freestyle best of 21.98 seconds in finishing runner-up to Loughborough's Andrew Weatheritt.
There were British records set by Loughborough's Adam Barrett, who lowered the 100m butterfly best to 50.05 seconds, and Lizzie Symonds who regained a share of the 50m backstroke mark in 26.45 from her regular sparring partner Georgia Davies. And the Bath-based Olympian relished a semblance of a point proven to British Swimming following her omission from their Lottery-funded squad and the team for this week's European Short Course Championships.
"I've mixed emotions about it," she said. "There's a sense of the pressure being taken off. But a lot of my contemporaries are at the Europeans right now. I wish I was there. I should be there. I've posted times racing against the best in Europe. That time tonight would definitely have been in contention for a high place. So a lot of this was about proving to myself and everyone else that I'm still there, and I'm still the swimmer that I was, after a disappointing year."
Elsewhere, Sophie Smith was just 1.5 seconds outside the British 200m individual medley record in pulling away from both Anne Bochman and Simmonds but the Loughborough came off second best to sprint specialist Amy Smith in the 100m freestyle final.
Today's highlight is the battle of Scots rivals Craig Benson and Ross Murdoch in the 100m breaststroke with both bidding to send out a signal to the absent Michael Jamieson.