Suggest me - how do i start my ionic learning journey

I am a php developer. I know ajax. Now i am planning to start a course in udemy.

I see a course on angularjs 1, then a course on angularjs 2 and then

a course on ionic 1 , a course on ionic 2 is being made by the instructor of ionic 1.

Can anyone please guide me the right path ? I do not wish to start from a wrong direction.