The Dutchman rushed back from international duty last week to complete the transfer from Arsenal to Old Trafford for a fee of £24m.
The 29-year-old has only had a handful of training sessions with his new employers, and Ferguson says that he will leave the decision until the very last minute.
"He hasn't played much. We are going to assess him the next couple of days and chat with him, see how he feels himself," Ferguson said.
"Adrenalin will help, if I choose to start him, but I think it's important he had a training session on Friday morning and hopefully the weekend will give me a good idea on whether he should start or I should put him on the bench."
Manchester United start their Premier League season at Goodison Park on Monday night.