How long before SP2 gets released?
It can be anytime within 1-2 weeks from now.
It went early visibility release yesterday (Jan 20th, 2016).
If you participate in the EV program you can download it.
You can check the schedule on SOLIDWORKS.com after login in.
The EV is there so it shouldn't take more then 2 weeks now.
You will also find the Technical alerts and news page interesting:
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