Thank you for your question! I encourage students even before their senior year of high school to start looking for scholarships for which they might be eligible when they become a senior. This gives them a head on finding scholarship opportunities. They can bookmark those scholarship webpages, or use scholarship websites that allow they to create an account and save those scholarships for future. Students should start applying as soon as those scholarship applications open for them in their senior year (or earlier). There are scholarships that are open to even younger students so it doesn't hurt to start looking early! Some places to start looking for scholarships are
https://www.cappex.com/scholarships/. For information on need based finacial aid,
www.studentaid.gov is great resource.
One caveat that students need to know is that when looking to fund a college education, only a small percentage of the total financial aid funding comes from outside sources, so spending time developing a college list that has schools that are generous with need-based or merit aid is more important than spending hours searching for smaller outside scholarship dollars.