The Glasgow player is part of Andy Robinson's 39-man preliminary squad and will be keen to avoid a repeat of his experience four years ago, when he dropped out at the same stage.
But he said: "The last one doesn't really enter my head. It's all about this one, trying to make sure I play well enough to get there and get selected.
"And then if I do, to make sure I do myself and the team justice with my performances.
"I can't control what went on four years ago. I moved on pretty quickly from it and I think that helped."
Kellock was one of five Scotland players sidelined from club rugby by head coach Robinson in March, in order to ensure their fitness for the World Cup.
Kellock and the others - Richie Gray, John Barclay, Ross Ford and Allan Jacobsen - have all been told they will face Ireland at Murrayfield on Saturday in the first of two warm-up games ahead of the New Zealand tournament, with Robinson due to name his team today.
The Glasgow forward missed the first half of last season following knee surgery but returned to captain Scotland during the RBS 6 Nations, and he feels in fine fettle ahead of the international.
"I'm feeling good and we've had seven weeks of a pre-season," he said.
"We have worked really hard, been pushed hard and everybody is driving each other on.
"It's been quite a long while since I played a game but it's been a long time for everybody.
"The body takes a bit of getting used to the bumps and bruises again after we resumed contact but it's good to get back to it.
"The game gives you a focus. It's going to be a tough game.
"With the first game of pre-season being a Test match, it makes sure we have to be up to the right intensity straight away.
"The training has been geared towards making sure we get everything we can out of these games - they are very important in the build-up to the World Cup."
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