Taking STEP 2 & 3 in year 12?

Some context: I’m currently in year 12 and hoping to apply for maths, including at Cambridge (trinity hopefully) and very passionate about maths. I’m a pretty strong mathematician (averaging about 95% in maths and fm due to mostly sign errors etc) I am prepared to have no social life at all during my A-levels - this will probably be necessary

I have been thinking about taking the step papers this year (year 12 for me) and was wandering if it seemed attainable to get at least 1,1 at this stage or even if its possible to do them early?

I mainly want to do them because I think it would help my application as I haven’t done any olympiads or gone far in ukmt in the past, but also because I just think that the step questions are really fun.

So, does anyone have any advice or knowledge on the matter?

Thanks