Preparing for USNCO in 4 months?

I’m looking to get Honors in the US National Chem Olympiad (top 150.) At the least. Even better would be High Honors (top 50.) Firstly, would it be possible to study in 3 months for the local exam, from now until March, and then in 4 months for the national exam? I’ve only taken an advanced chemistry course, not AP, so I’m still probably missing some of the framework, but I’ve purchased Atkins and Carey from which to study. I plan to devote at least a half hour every day to studying, and probably more on weekends and breaks. I believe I’m bright and motivated enough to teach myself difficult material in short amounts of time, as I’ve already self-studied for several APs and gotten 5s, including studying for EnviSci in one weekend XD But anyway, is USNCO High Honors a possibility in this short time frame? I appreciate any response or advice; thank you in advance.

Yeah its possible.