I think the best thing to do is wait for the prices or the market to be stabilized before buying. The reason is if you buy now and the prices are still going down it's a loss for you so it's better to wait than to have loss. So, you can't tell if it's a great opportunity.
I think stabilization are not necessary because what if the coin are stable but did not hit the bottom from the retracement which can cause many trader will loss money as they were expecting into a greater bounce back though the market are still dumping because it will continue to hit the bottom price and then starting to bounce back.