Performance pathways
Your pathway into pentathlon will depend on a number of factors, including how much time you have available to train, access to coaches and facilities, and your level of interest. Naturally, your sporting background is also a key factor: if you are already strong in a particular discipline, you probably won't need to spend as much time training in that discipline as you will in the others, while you get going.
Fencing is generally the discipline which takes the longest time to master, and you may need to be training in it for some time before you start entering competitions.
With all that in mind, the pathways diagrams below provide guidance on where to start with training and competitions, depending on whether you are coming from an athletics or obstacle background (first diagram below) or from a fencing or triathlon background (second diagram below). Your training pathway is in yellow, and your competition pathway is in green.