Interesting to see mixed opinions here. Thanks for the input!
To be fair studying early does have it's benefits - tested and tried. I was wondering if this would be different for the ATPL content. The question is rather which of it would more firmly stay in the mind if studied early. I can imagine, say, Air Law would be forgotten quickly.
I had a look at some of the Principles of Flight questions, and to be honest I could answer nearly all of them with what I've learnt at university