Same answer most of us would give you. Easy fix if you go see a PGA instructor. Could be worked out with one lesson and practice at the range. Hard to fix something you cannot see. especially if you are not a trained professional. With respect.

You're too close to the ball. A PGA professional will be your best bet.

Rotation of the lower body through the swing may be the hardest thing to explain, and the easiest to demonstrate. In all honesty, even as a low handicapper for a few decades, it's still my biggest flaw. I'm usually the first to say not all PGA guys are created equal, find a seasoned teacher, pay a little more, it'll be worth it in the long run. Good luck!

get a lesson

Agree with all the above answers. Lessons with a good PGA pro would definitely help!

If not in a position to book lessons, something that's been helping me with this as of late at the range has been hitting the first 15-30 balls at 1/8th speed, very limited backswing, very limited hip rotation, and just allowing the club to naturally follow the swing plane with proper angles (using a small Alignment mirror from the rear-on view (the ones with the red swing plane line on them)). Hitting them at 1/8th power really allows me to feel the feedback on where on the club face it's hitting with each minor adjustment & seeing the result of the ball flight down range. Then the next 20 at 1/4 to 1/2 speed with a little more back swing and timing the hip rotation with the downswing, impact, & follow through. Then the next 30-40 with a Full swing (and occasionally going back to 1/8th to 1/2 speed hits in between as soon as I have a mis-hit to reset before resuming back to Full swing.

I'm not a pro by any means and probably not qualified to give any tips, but this has been very helpful for me.

Firstly, I agree with going to see an instructor, but understand thats not always easy.

I personally have this same problem, an instructor had me put an alignment stick along the the grip so it extends from the grip in front of your front hip. Then take half swings or even just 30-40 yard pitch shots and keep the alignment stick from hitting your left side as a righty (if you "cast" or extend early you will whip yourself with the alignment stick). Instant feedback, but it starts to sting a little bit if you don't fix it..

It did help me a ton to create the correct feel, and after the second day doing it I was no longer adding welts to my left rib cage. It's my go-to beginning drill at the range.

This is the exact drill I use and it helps so much

The most simple to explain and execute drill is the wall drill. Start in your address position with your glutes just barely off of a wall. I would suggest without a club because you may also be swinging way under plane...no idea. Anyway, in your backswing rotate your trail glute so that it presses firmly into the wall. Your transition will force you to drag your trail glute along the wall a bit and then during the downswing, you must keep the trail glute pressed against the wall while your lead glute rotates into the wall as well and ends with your lead hip pressed into the wall. The concept is easier to explain: in the backswing the trail hip moves away from the ball. In the downswing the left hip moves away from the ball. If you suffer with early extension your trail hip moves away from the ball but then on the downswing your right hip moves back towards the ball instead of staying back while your left hip moves away from the ball. In the golf swing you should always be moving away from the ball, not closer too it.

I've struggled with early extension for a very long time. some of the faults is hitting it fat, shanking shots that go right and other weird misses. But one thing I found that helped with my E.E is to learn how to push off my right foot before I start my downswing.
(the ball of your foot).
you want to recenter your weight back to the left side (RT hand golfers)
try to get your left hip over your left foot on the downswing by pushing hard off your RT foot to your left side. ( you'll start to grip the ground) its a shift not a turn, you turn after you've shifted but NOT before.

as Lee Trevino said "If you fix one thing you'll fix 4 or 5 others".
hope this helps

One simple question for those seeking help with their swing problems. Would you go online to get your car engine fixed? NO.

Why most of us on here always recommend going to see a PGA professional. They have to see your swing to see what the problem/problems are to fix them. Nough said.

I hear a lot from people to see an instructor. I'm starting to think that is the proper fix to most golf predicaments.
If you are unable to do that there are a ton of instructor videos out there for early release.

WATCH: This Finally Fixes Standing Up In The Golf Swing
Eric Cogorno on You Tube!!