The more pressing issues are stability and that of the peoples choice for Brexit. She needs to get our negotiating position crystal clear before invoking a. 50. Once we have a plan and a strategy to achieve it then she should address the issues regarding a personal mandate. I'd say she'd need to go to the country in the spring. She'd be a fool not to with Labour as it is.
But opposition parties baying for a GE from the get-go is not in the national interest and would be a case of people sitting on the sidelines poking sticks into those who are trying sort out a mess just for the shear hell of it. It would be better if we work together to get the best deal for the country going forward than to start making stupid arguments about what mandate May has to govern. We are not one massive trade union demanding a vote on every single issue before we can move on to the next thing. The country would drown in bureaucratic shite. We can be 'democratic' in good time, right now we need stability and leadership.