What do you wish you knew before you started gcse ocr comp studies

that its a big waste of time

There's quite a bit of programming, so if you're not currently very good at the simple bits, keep practising them (e.g. while/for loops) now before you start - it will make it so much easier.
The EQ they ask for theory are generally quite repetitive, so as long as you do some past papers and look at the mark scheme for them, you'll be fine

i thought there was programming but its not assessed?

most of paper 2 is programming. ngl the new spec is SO limited that you do the papers so many times you can easily get 9s in all your mocks. I did this all year with no revision.
I didn't revise for the real thing and managed an 8, we were the year with that demonic paper that OCR had to review for future students.
I honestly hated comp sci (especially because I was one of three girls in my whole class and the guys thought they were better than us). But I wish I hadn't stressed that much because it's so repetitive you'll be ok. We also finished content in yr10 so had ages to revise - may or may not be the case for you.

i am a girl too and not a single person i knew took comp sci
( i took it cause its easy to learn so its an easy gcse)

let me know

ngl I just expected all programming and no theory.. but shock of realisation hit
im not a fan of it and i just struggled with CPU unit
Thankfully finished the exams so no more 4 me