How do I know when I will PCS?

SPC Paxton are you a part of 3rd BDE, 1st ID? I know that the BDE is going away, so you should be coming down on orders in the near future. I would talk with your 1st line to see if they can find any info out for you and if all else fails contact your branch manager to see if you have been placed on assignment yet, and ensure you keep ASK updated with where you would like to go, you never know you just might get one of those locations.

Contact your assignment manager. First go to your Army Career Tracker (ACT) and see where your grade and MOS are needed. If you don't know how to use it, get an NCO to show you, they better know how.
Once you see available assignments, talk to your assignment manager and ask to be considered for a particular assignment. I would say email them first as they get phone calls all day and usually from someone whining about an assignment.
A good soldier goes where they are told but a smart soldier knows where they are needed.

Here in the land of the morning calm, when a Soldier reaches a point in his assignment I sit him/her down and ask where they would like to go. I then personally email the branch manager to find out if that option is available, and if not what is. Recently the HRC Commander and CSM Smith came to Camp Humphreys to talk with the NCO's and leadership about assignments. They currently have a pilot program going where all Senior NCO's are supposed to be contacted by their branch manager for assignment choices. Also they briefed us that if we have a Soldier wanting to PCS they should talk to the 1SG and have him email them. The numbers of Senior NCO's is minute to the number of Junior enlisted and Junior NCO's, so they can't contact everyone. There just isn't enough time in the day.
With all that said I would ask your first sergeant to contact your branch manager to see what is available. Also, if your unit is on the patch chart to deploy you may be fenced and nothing they can do for you at the moment.