its hard to really recommend a study plan of sorts, but with reading time, especially in further maths where there are a few explain questions, i'd actually say try and actually read through the paper first, the core and the modules, work out which questions you dont know how to do yet, ponder about them, start to plan your time, how much time you'll spend on the core, how much more on the first/second modules, and also work out which youd like to start with, if theres a module you particularly enjoy, start with that, as to ease into the paper somewhat
and i guess with further maths, checking is 100x more important that in methods or specialist purely because theres so many mistakes that can be made and because they can be costly
so do plan to leave time to check but you should develop a strategy
for example, i know that no matter how careful i work, ill make mistakes, so what i do is i go through the exam at top speed, and then go through the exam a second time at that speed, which picks up 90% of my errors, and then i have a strategic search, where i have a mental checklist of mistakes i know i make and i eradicate them, its worked well for me since last year, and since, i havent made any more careless errors in methods/specialists
the other method, which some of my friends use, is to work slowly yet carefully, and only have a glance over at the end, some people just don't make mistakes