OP if you have the flexibility to do this it would be a great way to see how your horse might fare on their own. The last thing you want is to bring your horse home and see how they do on their own only to find they are a stress case. Then you will feel pressure and rushed to find a friend.
And this depends on how available hay is in your area, but if there’s access to year round suppliers, I would not rush in to feeling like you need to buy a year’s supply right off the bat while you are still figuring out storage, suppliers etc. Yes you will likely pay more to purchase smaller quantities but that’s fine to start especially with only 1 or 2 horses. Then once you feel like you have found a good supplier and have storage sorted, by all means do the years supply.
Better to pay a bit of a premium while you get your bearings than to buy a years worth of poor hay, or poorly store a years worth that could then get ruined.
There’s a big learning curve to bringing horses home for the first time and nothing wrong with taking time to figure things out.
If you are trying to keep your workload reasonable, be very aware of how high maintenance some of these rescue/retired horses can be. I was offered a free lease on a retired mare that needed soaked cubes 4x a day and passed because that’s a considerable commitment anytime you need to be away for a good chunk of the day. And an headache in the winter when temperatures drop below freezing. Also consider while you may not mind doing the work on the average day, what does that look like if you have a farm sitter? Some may need daily meds and a certain amount of equine handling experience to administer. That changes who can look after the horse vs a horse that just needs some hay tossed over the fence.