The 22-year-old was told to expect up to a year on the sidelines after damaging his anterior cruciate ligament in the Scottish Cup semi-final against St Johnstone in April.
Naismith has since undergone successful surgery but is reluctant to push himself to make a quick return to action.
"I don't know when I'll be back and I don't want to know," he said.
"I'm not interested. I think the feeling in my knee will let me know when I'm back.
"I don't want to say, 'in two weeks' time I need to be doing this', and going for a target which might not help my rehab.
"I'm feeling good and the physio says I'm looking good. It's all been positive so far."
Manager Walter Smith criticised the Hampden Park pitch after Naismith caught his studs in the turf and left the field on a stretcher.
But the young forward has revealed it was actually a tackle by Martin Hardie moments earlier which caused the damage - and that the Saints man has since apologised for the incident.
"I've seen what happened on video and it was just one of these things," said Naismith.
"I think the first challenge did the damage. The second time my studs caught in the pitch, which stopped my knee from rotating.
"You play football and you get injuries and hopefully you come back from injuries. Every footballer knows that every time you train and play you could get injuries. It's all part of the game.
"I appreciated that. He didn't need to do it but he went out of his way to send a message which shows he didn't mean it.
"Players out there have had worse than me and come back so in some ways you look at it as if I was fortunate because it could have been much worse."