The 23-year-old's latest ailment has sidelined him since October - forcing him to miss November's autumn internationals and the majority of Leicester Tigers' season so far.
And though England return to action on February 6, Tuilagi insists his long-term health must take greater precedence.
"It's slow but it's getting there. No one's really sure how long it's going to take," Tuilagi said.
"When it first happened even the doctor said it would be six to eight weeks.
"With this you have to just take it day by day and make sure it's better before you try to come back. There are good days and bad days. Some days it feels brilliant and you wake up the next day and it doesn't feel so good.
"[The end of February is] ideal but I have to get this right. It's not like a sprained ankle where you can strap up and get on with it. I have to make sure that, if I need to take another week or two, I'll take it."