...If I were to start over, I would buy a good 223 bolt gun and shoot the barrel out learning to read wind, shoot off a tripod, off my pack, off or rocks logs etc. ..
I gather the thinking is the .223 is much cheaper to shoot in volume and super low recoil, so practice here first, develop good habits and trigger control and the move up to your "high power" hunting rifle. Sure, you could just start with your .308, but my guess is folks put far fewer rounds down range with a .308 than a .223.
To get really proficient you have to shoot a lot. A 223 is economical and has long a barrel life. At distance it will magnify any wind reading errors.
What's that old saying about "great minds working together?"
Here's a picture of my 3 Weatherby Vanguard rifles. On top is my .300 Wby that I re-stocked in Fancy walnut to fit me, and it is my favorite elk rifle. Below it are my .308 Win and .223. I lengthened their stocks to match my .300, and they all have similar triggers and Leupold CDS scopes. Other than recoil, when I shoot them, they all feel the same.
A couple of days ago I posted "...I go to our range at least once a week, all year. Part of every trip, I shoot one or two rifles from field positions at the steel gongs at 200, 300, and 430 yards. The Weatherby Vanguard chambered in .308 Win that I have now, I specifically bought for inexpensive, light recoil range shooting at these gongs..." What I didn't say in that post was the second rifle that I usually shoot every week was a Vanguard chambered in .223.
Like the posters above stated, the .223 is very economical and has very low recoil. I only shoot reloads, and for comparison, I load 84 grains of powder in my .300 Wby and I weigh each load. I load my .308 Win and .223 on my Dillon loader and just "throw" the powder charges, 45 grains in the .308 and 27 grains in the .223.
I actually shoot more .308 shells than .223, especially at the 430 yard gong because I can't hear the .223 hits as well as the .308 hits. And like FLS posted, wind drift is more noticeable with the .223 than it is with the .308 Win.
I enjoy ringing the steel gongs, and the more practice that I do with my smaller cartridge rifles, the more confident I am when hunting with my .300 Wby.