I agree with the other posters that you are not anywhere near ready to be starting horses under saddle yet, but saying anything further on the subject is just beating a dead horse. I also disagree with young horses carrying a heavier rider that early on in their life, but again saying more would be pointless.
Don't give yourself a timeline, timelines are for people not horses. If she's doing well, end on a good note, if she isn't ready for something don't push it because it's on the timeline.
Many people spend too long on groundwork without getting much of anything done. I personally spend anywhere from a few days to a few weeks on the ground before I am riding. The horses that take the least amount of time are the ones that don't have much handling. It's the retraining projects that buck, bolt, rear etc that take longer. A young horses doesn't need to know a whole lot about a lot in order to make a safe riding horse. As long as that horse knows a whole lot about a little, and those little things are important building blocks, you're set.
You do NOT need to drill things. Go through your groundwork and if something is good, move on.
I start with roundpenning. Can my horse move off a suggestion at a w/t/l? Can my horse change directions by turning into me? Can my horse draw in toward me? Can my horse disengage their hindquarters off my body language? If all of those things are working, I may only round pen for literally a couple of minutes. If something isn't working, work on it and don't worry about the time frame of your session. As long as you are keeping your horses attention, it's all good.
Then, is my horse polite about being haltered? Will my horse stand still and be relaxed for desensitizing to noise, movement and sensation? Again, you don't need to use a whole lot of things to desensitize to. A lunge whip, plastic bag, a lead rope and a saddle blanket are about all I use. You are teaching your horse to relax to stimulus that isn't asking them to move. If everything is good, move on. Again, if something isn't working, fix it.
Then, can my horse disengage their hindquarters off of pressure? Can my horse lunge at a w/t/l without putting any pressure on the halter? Can they disengage their hindquarters, move their shoulders over and go the opposite direction? Can they do a rollback on the lunge line? Can my horse flex laterally correctly? Will my horse back out of my space? Remain light when i'm leading and trot off in hand, not lag at a walk, etc.
Then of course the normal handling things; can my horse tie, can I pick up my horses feet, etc?
When the groundwork is good, repeat it saddled. I honestly don't get my groundwork that great before I do it saddled. As soon as the horse is safe to be around, everything is done with a saddle on. If I was less experienced, i would do more. Many horses get their panties in a bunch the first few times they are saddled and seemingly 'forget' how to do things they know how to do. Because of this, I do most of my groundwork saddled. Lots of people will turn their horse loose while saddled to get them used to it. I do not, I want it to be crystal clear what is allowed and not while saddled. While under my supervision I can correct a horse is they buck while saddled, if they're loose I can't. I also don't have spare saddles laying around that I'm ok with a horse rolling in.
When you get ready for those first rides, I highly recommend letting your instructor do it. A young horses movement is unbalanced and they need an extremely balanced rider to stay out of their way while they figure things out. I w/t/l my horses on their very first ride if they are relaxed enough for it. Forward is the most important thing, without forward motion you can't train a horse.
For more in depth information on how to cue for things, I have dozens of posts regarding this information.