Should I get 2nd/lightweight stroller now or....

With so many new products coming out all the time, I'm so hesitant to buy anything big too far in advance! My mom is buying us our main stroller and I know when our son (due March 2) is around 4 mos well want a lightweight second stroller. So that's about 8 months away . My best friend wants to get us something big (money isn't really an issue for her) and I'm thinking of asking her for the other stroller (maybe the city mini). Is it too early to get the other stroller?