Walcott, who turns 20 next month, is set to feature against Burnley in the FA Cup on Sunday after injuring his shoulder on international duty in November.
"It is very important to see how he will respond with his shoulder and I think he looks to be nearly there," he said.
"To have him back is great and he can be very good for us.
"However the difference between training and competition is different. Theo is very fit, but after that you have to get used to tackles and go into the challenges.
"You have to use your arms and shoulders to resist."