Slight Windfall and Delegation Advice

Firstly, I apologize if this post is scatterbrained, but i'll certainly do my best.

I recently got $18,000 deposited in my savings from grandma. Based on my current figures, it's looking like i'll be at around $16,000 in subsidized loans and $8,000 in unsubsidized loans by the time i'm done with school.

Now, the question: What would be the smartest thing to do with this chunk of money in terms of delegating between saving/investing (mutual fund/IRA), and paying off current debt?

In seeking guidance, I've had Roth IRA and VTSMX thrown my way in terms of places to put this money rather than just letting it rot at 0.01% in my savings, but my concern is that it would be nearly pointless to put this money away in an account like that for 2-3 years before I will probably need it to pay off my loans. My current thought is that I can pay off my current unsub'd loans and accrued interest ($4,170), and then possibly put the rest in that Vanguard mutual fund until I need it? (I am uneducated about this fund, and have been unsuccessful in finding out about penalties for withdrawing, and other need-to-know parameters). Would there be a better short-term fund to use? Would it be worth it to divide the remaining money to set up an IRA, and then put the rest in some fund? Or would that be splitting the money too thin making it pointless?

Possibly better to just put all of it away in the VTSMX until im done with school?

Any guidance is appreciated, also sorry about another student loan post, but I couldn't find any other posts close enough in similarity.