When one kept on waiting thinking that the market decline to a level that will be okay for you to buy at a cheaper price you may end up not investing at all. Some use to open thread asking such question and they will never return to even read what people have to advise them let a lone invest in the coins they are making an enquiry about.
do it without hesitation, but you understand enough about the coins you will buy, if you are in doubt and doubt so you don't do it at all.
find out from a variety of reliable sources so that you are sure to invest in it and then you check the growth, indeed market conditions are not always good so you have to be vigilant so that you don't experience other losses or failures.