When would be the best time to reclassify in your career?

Well if your ETS is March of 19, then if memory serves me, you won't be able to submit a reenlistment package until July of 2018. The best time to contact a career counselor is before the package submission period opens. This will give you time to prep a package, meet the requirements and then have it submitted on the first day submissions open.

If you're looking to reclass, I'd talk to the career planner now. This will give you a leg up to make you the most competitive for submitting a package. They should also tell you if there are any prerequisites that you currently don't meet. This way you can meet the requirements before you submit a package.

the Sooner you can get approval and support for Re-classing the Better...
the Good thing, is that there is more uses for an LPN on the outside than a MLRS operator... and the ability to go to RN or PA is wide open ... It's all Up to your Motivation...

Your best time to get this ball rolling is when you are one year out from your ETS (when your re-enlistment window opens). But, nothing says you can't put the bug in the ear of the Career Counselor now.