TS, just to note that there are many ways to approach the world of financial markets.
From what you have read and will be reading in this part of HWZ, some are individual counter champions, some are index/ETF advocates, some are traders and some are a little bit of all. You can read it up here, as well as from books and blogs, of the different styles of investment and trading (note: these 2 are different). Once you have read them, settle on one that you are comfortable with.
If I were you, it would depend on what I would do after NS. Here is an investment approach:
If I am going for further studies full time, the savings that I had would be in a fixed deposit (with fixed deposit rates getting favourable and the impending interest rate rise) for the years that I am schooling, and when I graduate this amount (along with whatever pay obtained from vacation jobs) would form up part of my emergency fund. When I start working, depend on my comfort level, allocate some of the pay to savings and some for investments, and the rest as expenses.
If I start working immediately after NS, take half for investment while the remaining half form part of the emergency fund basis. Then I will allocate my pay between these two, on top of my usual expenses.
In all, set a quota for your emergency fund (3/6/12 months of expenses/pay, or by a quantum e.g. $5K, $10K, etc). Then any spillover from my pay allocation for emergency fund will go to investment, starting as cash portion of my portfolio. Thence from there, allocate to equities, bonds, etc.
Caveat emptor, the above would be my style.