Should I write the DC 15 today or tomorrow? Can this paper boost morale?

You can give it today. Yes, it was made to be on the easier side.

I don't know about you but I gave IMS mocks yesterday. After 4 days of no mock (I give one each day), I fumbled. I scored as low as 46 marks. I got so angry that I immediately gave the next mock. This time I wanted to kill the paper. I scored 88 marks (back to my usual) . So, unless you can not get demotivated, go for a mock (any mock). The tension, apprehension and all stuff demotivates us. Hope this helps..