The 23-year-old has been out of action with a pelvic injury since Spurs' 3-1 defeat to Benfica in the Europa League on March 13.
When asked by reporters if Walker was a doubt for the World Cup, Sherwood replied: "I'm not sure we're concerned at that length.
"We're concerned immediately as he's not fit and it is very doubtful if he'll be fit for next week as well but we're hoping to see him out there on the training field as soon as possible.
"He's still got a lot of time before the World Cup and there will be a few friendlies for England as well."
England will begin their campaign in Brazil with a group clash against Italy on June 14.