Most juniors think about recommendation letters in September. By then, the best teachers have already committed to 15 other students and your letter becomes a chore instead of a priority.
April is when you lock this in.
Here is what actually matters. You need two teachers who can speak to how you think, not just your grade. A teacher who watched you struggle with a concept, push through it, and then help a classmate understand it will write a letter that moves the needle. A teacher who only remembers you got an A will write something generic that admissions officers skim past in 30 seconds.
Think about which teachers have seen you at your most engaged. Not your easiest A. Your most engaged.
Before the school year ends, have a real conversation with those two teachers. Not an email. Walk up after class and say something like "Your class genuinely changed how I think about X, and I would be honored if you would write one of my recommendations." Then follow up with a brief document listing your activities, your goals, and two or three specific moments from their class that stood out to you.
That document is the difference between a forgettable letter and one that makes an admissions officer pause.
Who are you planning to ask, and what class were you most intellectually alive in this year?