"I didn't claim CCA for vehicle for my small business from 2012 because net losses every year until 2017 can I claim all CCA in 2018 as business has net income?"

No, you can still only claim a maximum of 30% CCA. The one "upside" to this is you miss out on the half-year rule and get to claim the full 30% on the value of the vehicle when you actually added it in 2012. 

Here's a little more info on CCA from TurboTax: https://bit.ly/2NUNalo