Try to work up the new callous using a light touch. And then try to keep a light touch if you can. In 25 years of playing electric bass regularly, gigging several times a month, I have yet to have callouses on my plucking fingers. But, I also use a bit of fingernail, too, so it's a tad different for me.
2001 American Series Jazz Bass / 1987 Jazz Bass Special
Markbass Little Mark III / dual 151P cabs / 121H combo