Your stated requirements were vague, basically "parse an OBJ model and display it to the screen with a basic shader". This as stated can be done very quickly, in a matter of days if you work hard at it. Of course, adding requirements and features will increase the time accordingly, but you did not mention these in your question, they were therefore not mentioned in the answer.
I'm just pointing out that people don't usually write rendering engines from scratch anymore (the one I wrote in 1997 is still working fine thank you), and if someone tells you they can write a rendering engine from scratch in 2 days they are lying.
Your two posts are somewhat inconsistent with each other, is there something you're not telling us?