Dwarf Nectarine Curl

Hi all. I have a dwarf nectarine tree. This is its 2nd year and it’s had leaf curl again. I treated it last year with a spray the garden centre recommended but it didn’t work. Now I understand about sulphur and have it ready for winter and spring. The tree looks awful now, the question is should I trim it or leave it looking awful until it’s time to spray it? Many thanks Sarah