First, prepare for GRE.
GRE is totally different from TOEFL. Though they both are English proficieny test. But in GRE you have to study Quants too.
Second, GRE score is valid for 5 years. Means if you are planning for master after 2 years, an you think you are ready for GRE, you should take your GRE now.
And, generally universities consider your TOEFL score from last 12 months. SO if you are planning to go for masters in 2018 and you take your toefl now, this will be total waste of money. As this score will not be considered at that time. But GRE will be considered for next 5 year. For some universities GRE score is valid for 3 years, and for some it is valid for 5 year.
Another thing, GRE is like a marathon. You will automatically cover some part of TOEFL while preparing for GRE. But for TOEFL, you have four sections, Listening,reading,writing,speaking. As you can see, there is no listening and speaking sections in GRE. And these sections need time. But 1 month is sufficient to train you mind for these two sections. Reading is same as GRE. Similarly, writing is same as GRE also has AWA section.