If you're entering the fourth month of NLP and you've gained a total of 9 lbs, then YNDTP: A Clarification | Mark Rippetoe
I don't know how tall you are, but 4kg in 4 months is not the novice program, which includes eating, as repeatedly mentioned in the article.Originally Posted by Mark Rippetoe
That said, you've put some decent weight on the lifts considering you haven't eaten properly. My suggestion is not to do a light day, but to up your calories significantly, so you gain weight and don't stall. Get yourself to 90kg by new years and I bet you won't worry about stalling. After that, implement a light day mid-week, sure, and your LP shouldn't last much longer than that anyway.