This is a good plan, but I would prep maybe once for the week--tupperware and freeze or refrigerate. That way you can just eat when it's time and not prep every couple days.
Of course, if you have a lot of extra time or you just enjoy cooking that's cool too. Lots of people do, but I am personally not like that. I find the busier I am the more important it is to prep for a week--or at least M-F work/school days--in advance. Cook in batches, saves time.
You said you have been eating 3500 calories/day. My next bit of practical advice is this:
- Log your food intake and times that you eat. Minimum log calories and protein for sure to make sure you're getting enough. You don't know how much to increase your food or what foods you are short on if you don't know what EACH day is looking like
Second this keeps you from getting stuck in the "I can't grow but I eat a TON!" mindset. If you're eating, you'll know exactly what and how much...and if any days of the week were subpar. Some slight variation in calories is normal of course, but if you're going from say 3500 to 2500 because you got busy and forgot to eat or prep meals this will tell you so you can fix it faster and waste less time.
Don't jack your calories up by 1000 a day all at once--that's a fast road to fat gain. Do it in small but measurable stages: extra 300-500 for a week, see if the scale moves. If not, add another 200-300 and check in another week, etc.
Wait until the scale stops moving for a whole week or 2 to add calories. Then repeat the above steps.
You as a naturally skinny guy have to worry less about getting fat, but it is still possible. Don't become worried about losing your abs, because that will short-circuit any chance of piling on muscle and the truth is you have to lose fat to get contest ready anyways. But the flipside is, don't openly invite extra fat gain by making a habit of eating crap or jumping 1000+ calories from your present level all at once. You want quality gains, not a dirty bulk. Also, eating more crap makes your tastebuds start to crave that crap--and that is a recipe for disaster later in life.
Just remember--super clean doesn't mean "chicken and rice" for every meal. You need the vitamins and fats in different food sources, so healthy variety is key.
If you're like some people (including me) who don't mind eating the same thing every day, just make a list of meals where every meal is different and eat that every day. Still allows easy shopping list because you know what you're getting, but your nutrition is more well rounded. Example:
meal 1--4 eggs, 1/2 avocado, 2 slices toast
meal 2--6 oz chicken breast and rice with coconut oil
meal 3--8 oz steak and potatoes and carrots
meal 4--salmon and salad with olive oil for dressing
meal 5--protein shake with milk and peanut butter......etc.