You don't give alot of info about your self. Take out a DC3 corse, study and pass the EOCT. If you can strike where your at try to do so. Apply to school. If and when you get DC school you will be that much further ahead.
This is an age old question I get everyday. I am an instructor at Boot Camp and alot of recruits ask me this question.
First off guaranteed A school is dangerous. I went to guaranteed A school and when I got out to the fleet I knew alot of DC related stuff, but almost nothing about anything else. Also it seemed alot of the people in my A school class didnt know what being a DC was and I believe some of them would have been better off going other rates.
As for A school over striking it depends alot on your situation. If you go to a unit with no DC's or DC's that are not willing to work with you to strike then obviously you should go to school. Alot also depends on how you learn best, I have had four people strike to 3rd underneath me and they did great in the fleet. I think A School is great because you get all the correct info fed to you in a specific timeline, I think in most cases it is faster to go to A school(Depending on the school list.) Your best bet is to put your name on the list and start striking and see which one comes available first.