When is it a good time to invest in Cloud mining? I bought bitcoins a while ago, an investment, but have now been reading up on cloud mining.

Due to the cost of bitcoins rising, is now a good time to invest in cloud mining?
TL;DR: Never.
Lack of Control
I don't think there is ever a good time to invest in Cloud Mining. I remain utterly unconvinced of the whole business model.
Mining itself already has an inherently slim return rate, then putting both your investment and the hardware into the hands of a third party that wants an additional cut seems counterintuitive. With regular mining you can at least switch the pool when you are dissatisfied, with Cloud Mining you make yourself a hostage to changing circumstances.
Scams in the space
Definitely have a look at Cloudmining 101 (ponzi risk assessment). There are a lot of scams in the space.
Buying bitcoins directly may be better
A lot of people interested in investing into Cloud Mining point out that it may be a profitable investment if Bitcoin prices rise in the future.
Under the expectation of rising prices, the reader should consider the value increase of the same investment directly into bitcoins instead, though.

Also see this related question: How do cloud hashing companies profit? (leasing hashing power).