Got a few grand in cash from relatives for newborn. Is it time NOW to invest and hold long term??

With stocks falling from trump's tariff threats among his other threats, wouldnt it sorta be buying stocks/mutual funds at a "discount" right now? I see many S&P500 funds down 10-15% right now. Thinking about opening an acct for my daughter now because these will obviously bounce back and keep climbing 20+ years later.... please correct me if I'm wrong, thanks!!