Pre-Summer Internship Skill Grinding Help

Hello. I apologize in advance for the length of this post. I'm a junior economics major at a top-60 nationally ranked college in New York City. I am interested in the JP Morgan Corporate Analyst summer internship and I'm thinking about applying before the deadline in March. I have a 3.5+ GPA and past internship experiences in consulting (A start up) and business management (A real estate brokerage and an international business firm). However, I am not very confident in my ability to compete with some of my peers in terms of excel skill, financial modeling and overall financial knowledge...I have basic proficiency and experience in excel (Spreadsheets, data-input) and have some understanding of financial and business concepts, but I have no knowledge of financial modeling. How can I efficiently study the market, financial modeling, and excel on my own so that I can reach a competitive level before the March deadline? What other technical skills do I need? I am willing and prepared to put in the work necessary. Please help comrades.