The 22-year-old winger joined the League One club last week on a season-long loan.
Johnson played 90 minutes in the loss to Burton Albion less than 24 hours after signing with his new club.
Asked about the winger's performance, Evans said: "The kid had a decent debut.
"He delivered a few superb crosses in the first period but he lacked quality service in that period.
"In the second half we pushed him up top and he created a few problems, he will be fine for us."