BoredSaint is right, what separates the very best students and the good students in Mathematical Methods is not their knowledge or understanding of the course but it's the amount of silly mistakes and errors they make as well as raw experience of doing exams...etc

I personally think that if you go through it the first time, before you start on it, you do it properly, like don't take it half-heartedly because if you're in that situation, you're better off just letting it be and just keeping slightly ahead of school. Because if you don't do it in detail and you don't do it properly, but rather you're rote learning or memorising rather than understanding the concept, you will forget, and believe me you will

- I think this is what Rohitpi was suggesting in his post.
In Methods, you can probably quite easily finish the whole course in detail over the holidays, but with Specialist Maths I'd advise against doing that purely because it's a subject that's much more disjointed than Methods, they have purely separate topics sometimes, not like how Methods is really all inter-related. You will forget a lot of Specialist Maths if you do it that way.
So maybe don't go through all the topics, but go through the important ones. In Specialist, go over the Integration, that's a topic that is heavily related to concepts, it's also the foundation to basically half of the Specialist course, then after that I'd go through the individual chapters such as Vectors, Complex Numbers, Graphs, Trig...etc. Kinematics/Dynamics aren't hard, so just let them be for now, you can do them in the June Holidays or the April Holidays

But if you don't have time, it will be much, much more beneficial to finish the Methods course

so go all out on that