How bad can my prelims be if I’m aiming for raw 11 O-Levels?

Hi, I’m a Sec 4 student taking O-Levels this year and my goal is to get around raw L1R5 11 for my O-Levels.
I’m wondering what kind of prelim L1R5 I should realistically be aiming for to know that I’m on track. I know prelims can be harder than O-Levels and that people can improve quite a bit between prelims and the actual exams, so I’m not expecting my prelim score to be exactly 11.
For those who got around raw 11 (or similar) for O-Levels, what was your L1R5 for prelims? And how much did you improve between prelims and O-Levels?
Would getting something like 15–18 for prelims still make raw 11 realistic, or would I need to be much closer to 11–13 already?

Just looking for some realistic benchmarks/motivation because I genuinely have no idea what’s considered “on track” 😭