I don't want to slow down your enthusiasm, only those sections are really long. Newbies sometimes underestimate the time needed for editing. So I'd advise you to stick with the two sections you already claimed for now and when you can see how long it takes and you come close to the end you claim the next sections.
Usually there is a two months deadline. I am not very strict in this project, as you can see in the MW, as this is a kind of complicated text. But I do think it is maybe less frustrating to claim less sections at a time instead of taking on a huge pile and having the pressure to finish them.
Chances that the sections are still open in two months or so (whatever time you need for the sections you claimed) are high
If you want to claim them then I'll be more than happy to give them to you