Hi milkybar,
There's no real harm in taking the GMAT soon (so that you can get a sense of how facing the Official Exam might differ from how you face your practice CATs/mocks), but it will cost you some money - and if you do not think that you will hit your Score Goal, then you have to decide if the 'experiment' of facing the Official GMAT is worth that expense.
Your Verbal Scaled Scores from your first 3 CATs are all around a V26, so this recent V30 either means that you have been improving your overall Verbal skills OR that you got a bit lucky (re: on a few questions, you narrowed the answers down to 2 choices and 'guessed' correctly). Based on the information that you have provided - along with your Score Goal - you will likely need at least another 2 months of consistent, guided study before you could get to the point that you could consistently score 720+.
I suggest that you study however you like for the next week, then take a new, FULL-LENGTH CAT so that we can see if you're actually performing at a higher level overall at this point. Make sure to take the CAT in a realistic fashion (take the FULL CAT - with the Essay and IR sections, take it away from your home, at the same time of day as when you'll take the Official GMAT, etc.). Once you have that score, you should report back here and we can discuss the results and how best to proceed.
GMAT assassins aren't born, they're made,
Rich