My stupid advice is not to buy any alts any more in this not-her-not-there market. Just keep your baskets as diversified as they are. And then keep adding on to the big coins. Bitcoin. Ethereum (I do not like it but there you go). Litecoin. Everything is too risky now. Floors look like floors until new floors are found in basements we never thought would exist again. You buy more alts and you "sell" Bitcoin too, so it is a double edged sword, is it not?
I am in the opposite side, I believe in newer good alts more than the "big" coins.
Re: bottom, yep...no one can really tell where it is so we go with our gut. Sometimes we win, sometimes we lose. Such is life.