When can this card be used? Does immediately have to be used after their turn, or any time within their turn?
I ask this because of Get me Solo (Search for Skywalker), I was wondering if it could widdle around it?
For example drawing before force phase ends to that they hopfully used there resource.
Also when are you too late to grab it?

Ranji said:

The Mission Briefing effect (draw a card at the beginning of the opponent's turn) happens immediately when the other person starts (balance phase) so you have to draw that card right away if you want it. Get me solo can be used whenever you want on your turn but the you must pull the card you want to discard (if you guess right) immediately.

Mission Briefing has a Reaction ability. Reactions can only be used immediately following their triggering condition. In the case of Mission Briefing, that means that you can only use it immediately after your opponent's turn begins.

Get Me Solo is an Action ability. Action abilities may be used in any action window. Both players alternate playing action abilities in every action window, starting with the active player, until both players pass consecutively. Additionally, Get Me Solo requires that you play it during one of the action windows on your turn. For a full breakdown of when action windows occur, see the flowchart at the end of the rulebook.