cob or formal? help!

Hey y'all, Next fall I will be a sophomore here at UA. I decided to go through Formal Recruitment next year until my friends already in sororities started suggesting COB. I come from a middle class family and since my parents don't find greek life fundamental for my college years they won't pay for my dues (just my meals). Instead, I will pay for the sorority myself. As for now, the money I save/earn is per month and if I do COB I will struggle to pay the whole semester dues on the first month of pledging/before initiation. I will need to make monthly payments or go through a payment plan. However, I feel like my chances as an upperclassmn are higher if I sign up tomorrow for COB. I was wondering if I should just wait for Formal Recruitment and focus on getting rec letters and finances this semester or just go through COB as I am right now. My GPA is 3.5