For me, leasing scares the bejesus out of me. I have seen and heard of so many horses/ponies going into reputable programs and coming back soured, lame, improperly cared for etc, etc. Taking people 6 months- year to get them back into shape, feet corrected or never getting them back the same and having to throw them out on pasture to hope they get better.
I purchase my ponies as yearlings/ 2 year olds (or even as the OP has a line on, green and ready to go) so I can purchase them for a cheaper price and then start to get them out to line shows and get the idea of showing. Does not have to be A shows, schooling shows are totally fine. Just the atmosphere and getting them out is a great start, great for video’s and sales promotion of course.
I tend to start my guys as 3 year olds lightly, maybe ride them around at a show in the fall, then start them over fences as a 4 year old, show them for the year at the 18" height (hey as an adult, I don’t mind doing the long stirrup division!) to put a good start on them and then sell them as a going, late 4 year old (w/t/c, changes, and going over small fences). I have been getting in the low/mid 5’s for my ponies and I’m able to keep them at home for better cost savings (though I sometimes board out for the winter months to keep or get them going, so that ups the cost a little, but its also my winter enjoyment). I’m just too scared to lease out and get something back all messed up - especially ponies of course.
I did do a free lease on one of my 4 coming 5 year old ponies over COVID as I didn’t have any kid riders for my medium - he was only adult ridden by me. He went to a great kids program (one that I actually do trust) and he got kid miles for the year and I sold him to one of their clients that fall. So it did help with his sale getting him out there and having real kid miles, but it was scary for me at first, I’m not going to lie. My husband wanted me to keep leasing him, but I refused to do so worried I would get a wrecked pony back. I was happy to sell him and not continue leasing him on though he has done really well with his kids and I probably could have leased him and made a lot more $ then just selling him as a 5 year old (this is now 4 years later and he’s showing well on the A’s in the medium division). My husband reminds me of this to this day still
This of course is just my $0.02. I’m not a pro, I have a teeny tiny little program (I’ve sold about 8 ponies over the years so far) and I only take on 1 sales pony at a time and can keep them for several years before I sell them on depending on how old they are when I purchase them.