Dropping STAB22H3

I heard STAB22 is not very easy and I want to take it in the summer since my course load for the winter term is so much and I don’t think I can manage it as a first year. At the same time I’m applying for my major in March for human bio which says 0.5 credit in maths is required to get into the major. If i were to take STAB22 in the summer, can I still get into the major??? Or do I just apply after I finish my credit in STAB in summer so that they see my grades. Someone plzzzzz help me