Is it possible for someone to awaken the Mangekyou Sharingan before they even awaken the Sharingan?
To be honest, I believe the death of the whole clan (especially the death of someone's parents by one of their own siblings - Itachi) is more traumatic than anything and when Sasuke with all those emotions could never achieve it in such a long time, I am sure it can not be achieved without achieving the basic Sharingan levels.

And most importantly, you can not simply do a maths questions without knowing the basics... So basics, i.e Sharingan must be present before the awakening of Mangekyou :)

That is simply what I believe, what is in the minds of Masashi, we don't know :P