After Knicks rookie Kevin Knox’s 4-of-16 shooting performance in the season opener versus the Hawks on Oct. 17, his father took him for a drive. They piled into his truck, drove straight to the Knicks’ Tarrytown practice campus, turned on the lights and worked for 90 minutes — until 1 a.m.

“I saw couple of things and we fixed it,’’ Kevin Knox Sr. told The Post on Saturday from his home in Tampa, Fla. “That night we were shooting, working on the fundamentals.

“He came out against the Nets and everybody in the whole world saw he had a better game. Truly in my heart, if he didn’t sprain the ankle, he would’ve gone on to more good games. We got back to the basics. I was the first person to show him [shooting] form. I know what to look for.’’

As Knox rehabs from the left-ankle sprain he suffered Oct. 20 against the Celtics, the NBA’s second-youngest player, at age 19, is in good hands.

Knox Sr., who won a national football championship as a Florida State receiver and was drafted by the NFL’s Bills, is renting an apartment in White Plains with his wife, Michelle, to be close to his son and help ease his adjustment during his rookie season.

“Just like the golf swing with Tiger Woods, his dad, Earl, would be able to say, ‘Look at that,’ and we know what Tiger went on to do,’’ Knox Sr. said. “I’m like Earl — or any father who can give his son good, sound advice. What I told Kevin that night, just know this is the things real pros do. Kobe Bryant is famous for it. If he had a bad shooting [game], he’d stay in the arena and get shots up. These are things he has to do and I want to give my son a good foundation.’’

The Knicks have not announced a timetable for Knox and he hasn’t been made available to the media.

But his father told The Post the timetable is roughly 2-to-3 weeks. He says his son is expected to return anywhere from Nov. 2-10. According to his father, the injury was not “a high ankle sprain’’ but a less-severe “Grade 2.’’

Knox Sr. said he was so happy he was in the stands to offer immediate moral support. He said his son is “champing at the bit to get back,” especially since he snapped a severe shooting slump dating to the preseason when he exploded for 17 points in the last-second loss to the Nets in the season’s second game.

“He’s like, ‘Daddy, it felt so good [in Brooklyn], I figured some things out,’ ” Knox Sr. said. “The most important thing I told him is you have 78 more games left — not to mention a lot of New York is hoping you have a 15- to 20-year career. When you put that in perspective, you don’t try to come back right away. It’s not the NBA playoffs.”

Knox took shots during Friday’s practice.

“You want 110-percent pain free,’’ Knox Sr. said. “That night he was a 9 as far as pain. Now [Friday] he probably is a 3.”

Knox’s shooting went to pot in the preseason’s final three games. The 6-foot-9 forward out of Kentucky finished at 32.7 percent in the preseason, prompting coach David Fizdale to remove him from the starting lineup for the season opener.

“It was a surprise and a great thing,’’ Knox Sr. said. “When you come in as a head coach, you’re trying to accomplish having a great culture. His culture when I talked to [Fizdale] was, ‘we have to compete and play hard.’ If he felt Kevin wasn’t competing to the highest level and someone else outplayed him, so be it. I told Kevin go in the store, buy a yellow hard hat, bring your lunch pail and let’s get to work.

“This is why they made a change because that means you must’ve not impressed, so we have to continue to get in the gym and put up a 1,000 shots. Because of God’s DNA he gave you, you’re going to make them. We saw what he did in summer league. We know he can shoot.’’

Knox also has gotten advice from former Heat stars Chris Bosh and Dwyane Wade.

“Dwyane Wade told us there is no school or other things to worry about,’’ Knox Sr. said. “Whatever got you here, which is basketball, make sure you keep it about basketball.”

In repeating a Fizdale sentiment, Knox Sr. said he isn’t as worried about his son’s low shooting percentage and hopes he’s never afraid to let it fly. Knox’s best attribute, scouts say, is creating good shots for himself.

“As far as efficiency, we just want him to be aggressive,’’ Knox Sr. said. “Be Kevin Knox the ninth pick and get shots up. I don’t think he picks and chooses his first year. We know he can put the ball in the hole. We saw that against the Nets. Efficiency, I’m not sure that’s really in my opinion that important. You take good shots, they’ll fall.”