Congrats on starting your DIY soylent journey!
You want to mix up a day at a time, both because it’s easiest to read off the measurements directly from the recipe without doing any further calculation, and also to make sure that you’re getting an even mix of nutrients every 24 hours even if you haven’t blended everything perfectly uniformly.
Of course, you’ll probably want to mix several days’ worth in one sitting for the sake of efficiency (I’d probably shoot for once a week, after I’ve finalized a good recipe for myself - I’m still experimenting). Just do one day at a time to minimize deviations in nutrient quantities.
For a sense of how to mix everything up, refer to this video:
That’s what tipped the scales in favor of actually giving this DIY thing a try, for me! I’d recommend dumping the ingredients in a mixing bowl though, instead of a plastic bag, and then transferring from the mixing bowl to a plastic bag for shaking at the end of every (day’s worth) batch. More efficient that way. You can reuse the plastic bag - just keep it to dry powders and you won’t need to wash it.
Once I mix up a day’s worth of powder, I’ll split it into three containers (one for each meal) and add the oil. Each morning, you can take the day’s allotted mix and put it in three blender bottles. I just fill each bottle about 90% of the way with water, on top of the dry mix that takes up maybe 30% of the bottle. That way it’s not too watery or too thick. Adjust to your taste, of course. Shake up the bottles and let them sit in the fridge to chill until you need them. Just one day at a time though!
For the extra calories, I’d recommend more oil (fats) since People Chow 3.0.1 already has a ton of carbs (too many, in my opinion). Try bumping the soybean oil to 100g per day - that will bring the total just over 2400 calories, without really overdosing on any other nutrients.
I’m no scientist or doctor or nutritionist though, so do what you think is right!