Jogging is one of the things that the Kinetix 300 does not do well. It's really made to be an indexing drive.
The way I've done it is to select an index position that is beyond the limits of the machine, then use the Abort Index command to end the jog.
As for doing that before the Kinetix 300 knows its position via Home... that's a tough one. The drive can't know where it is until you've told it where it is.
Maybe doing an Immediate Home will work, but then the drive is just working off an arbitrary position. You would have to alert the user that the drive isn't ready to use, or write your program so that it can't do any real indexing until a home-to-limit is done.