personally I don't believe in cloudmining sites. because most of them went ponzi. but something doing is better then nothing.
what you think guys. how much should I invest first?
IMO now is not the best time; I would wait until the S9 is announced and preorder is opened. When this happens the market for S7 will go way down. Do the math now and find out what price is most likely profitable for you; the S9 will have high markup initially, and the S7 exodus should drive the price down enough to make it the better buy.
Agree, this is not the best time. However, buying S9 immediately after the release, in my opinion is not the best solution. As I remember rates S5 and S7 they were very overpriced, with S9 I expect a similar situation.