Hi Hannah, and welcome to the forum!
Firstly, will your horse be living on your property or someone else's? In a paddock or a stall? Which area (roughly) do you live in? What are your winters and/or summers like? This will help us determine what feeding schedules are needed. It will also depend on how easily your horse "keeps" i.e. how much feed it needs to keep a decent weight, and how much hard riding you're doing with it.
With my horse, if he was stalled (not ideal IMO, they get bored quickly in there), I take out in the morning, remove whatever rug he may have on, do a quick groom, exercise him, muck out his stall, put the feed and water in and put him back in. Then in the evening I go back, do a more thorough groom, ride, muck out, rug and feed before sending him to bed.
I've never had my own property but when my horse was living in someone else's paddock about an hour's drive away I was only able to get down there once a week. The property owner managed his feeds and rugging, so I would go down and groom, ride and groom again. That was sufficient for him to have a very glossy coat, because his diet was so good. He was being fed twice daily at first but he got VERY fat so ended up only getting a hard feed every second day. He had plenty of space to exercise himself (but the lazy bum chose not to!
Best of luck with your near-future acquisition!