Prep Time for Technicals

Hi all, high school senior here. Because of the way our curriculum (Southern Hemisphere) works, I'll be graduating this November and will be entering college next year. I plan on getting an internship at a boutique bank, hopefully for a 2-3 month period so I'd have time to chill too. I'm hoping this helps my resume when I'm applying for internships in college, but even if it doesn't, I think it would give me a taste of the industry and enable me to decide if IB is something I really want to pursue. I don't want to come off as a complete goober when requesting for internships, so I'd like to have at least some degree of knowledge.

Here's my question: How long does it take for someone with minimal technical knowledge (very brief knowledge of DCF models only) to build up enough knowledge to land a meaningful internship at one of these smaller boutiques? Thanks for reading.