Capitalizing on market crashes is key to retiring on time. Many millennials are still looking for their first chance.

• Stock market declines can create bargain-buying opportunities for investors looking to generate long-term wealth.
• Many millennials are looking for their first chance to participate, having lacked adequate savings during prior market downturns.
• Experts say millennials shouldn't necessarily wait for a crash to start investing.

When the stock market falls, people with investment portfolios or a 401(k) generally see their wealth suffer. But, perhaps counterintuitively, those same patches of weakness present millennials the opportunity to keep their retirement savings on schedule — as long as they're proactive and ready to put money to work.