We recommend starting from Magento 2.0 as this will give you a better understanding of core development principles. Magento 2.0 documentation has better coverage of use cases and workflows and uses many coding patterns that are not part of Magento 1. Additionally, there are also aspects of Magento 1 that do not carry over to Magento 2, so you would waste time learning some things you can’t apply in Magento 2.0.