I wouldn't use a #2 pencil,on any quilt at any time. I've seen vintage quilts that have been washed many times and the pencil lines are still there. Those that have had no problems with them washing out may be living under a lucky star. And please, don't get mad at me - I was taught almost 40 years ago that this was a no-no. What happens if one day the pencil lines do not wash out? We are so lucky these days to have many other choices for marking quilts. If you are doing straight lines a good old fashioned Hera marker works great and only leaves a crease for a short time.
I apologize to to those who totally disagree with me.
Sandy in Mooresville, NC