If you have never done fire before just apply every where and prepare to move for the summer. It's hard to get a fire job if you have no connections or experience in the field. If you apply more places you have a better chance of getting a fire job federally.
If your looking to get into federal side get a profile setup on usajobs.gov. It's the federal job website where all jobs fed live. Once you create a profile you can make a resume and apply to jobs.
If you have a friend who has worked fed before ask them to show you the application system. It would be beneficial to have someone experienced show you little parts.
For fed jobs they have a pay scale known as GS. It starts at 2 and goes to something high like 16. 16 is like the secretary of the interior or politicians.
GS 2 is like "you have a high school degree but never used a shovel before entry level". The higher you go the more experienced you need to be and the better your paid.
If you have worked landscaping or labor intensive job before you could get a GS 3 job. Still entry level but you have worked labor jobs before. When you start getting to GS4 or higher you are expected to have fire experience or have a natural resources/outdoors degree of some sort.
GS5 fire jobs you start getting fire requirements which can take a while to build up.
And the list gets longer for qualifying for higher levels.
For when should applying to jobs, you should be looking at December January. Some regions might even post earlier.
The jobs you should be looking for are GS 2-3 level jobs (unless you have experience in fire or a natural resource degree). Apply everywhere and see where you get offers.
Things you could do to up chances of getting on you could take wildland fire classes. If your entry level they will give you these classes for free but you would rank higher if you had already taken these entry level classes. I took my classes in my college long ago. One place that is just wildfire classes I have heard of was in Colorado. I have not gone there but I've heard of good things. https://www.cwfima.com.
Also if you have wilderness first responder or emt put that on the resume. Wilderness first responder is easy to get or gives you a lot information.