One of the most beneficial aspects that I have found with the ISO 45001 format (just like all the other ISO management system standards), is that the document is written in the order that you would want to implement the requirements. So, starting at the beginning of the standard you want to first identify the context of the organization by identifying the internal and external issues, the interested parties and their needs, and documenting the scope. Following this you will want to put in place all of the leadership and worker participation processes, including documenting OH&S objectives, assigning roles and responsibilities, and putting in place the process for worker consultation and participation. You would then proceed through the standard, putting in place the processes and documentation required.
The one exception to this, is that it is helpful to implement the requirements of clause 7. 5 for creating, maintaining and storing documented information (procedures and records) at the beginning since this will be needed to document everything you need as you go along. The only other good advice I can give you is to split up the tasks and get started. You don’t seem to have a lot of time, and you just need to go through the standard and put in place the required documentation before the stage 1 audit so having more than one person working on this will be helpful.