The 16-year-old scored with his first touch as the Saddlers claimed a 2-1 victory at the Swansway Stadium.
Candlin, who netted twice in a 3-2 defeat Stafford Rangers last week, had only been on the pitch for three minutes before finding the net, after being brought off the bench late in the second half.
A delighted Whitney said: “For getting those two goals in midweek he deserved that chance, those ten minutes.
“As you can see he does not need many chances to take his goals. I think he is a natural goalscorer.”
Candlin fired home with eight minutes remaining to decide a game which had till that point looked destined to end in a draw.
Luke Leahy had put the Saddlers ahead in the first half after Simeon Jackson had saw an early penalty saved.
Substitute Nyal Bell then equalised for the National League North hosts at the start of the second period.
“From a fitness point of view I was really pleased,” continued Whitney, who chose to rest both midfielder Flo Cuvelier and defender Matt Preston.
“In the first half I felt we did enough to go in two or three up. It was nice to win the game, nice for Luke to get his first as well and from a set piece too.
“It’s great for Mitch to score too. Overall it was great to get some minutes into the legs. Reece (Flanagan) has a game under his belt. I thought my two centre-halves were really good again, very commanding.
“When the weather turned they put us under a bit of pressure but we came through and won it.
“Everyone says you have to get your first win in pre-season and we have done that.”
Cuvelier and Preston were both rested after taking part in a heavy training session a day previously. James O’Connor remains sidelined with a hip injury.
Whitney added: “We have rested a couple this weekend. We worked them really hard on Friday and that is part of the management of certain individuals.”