if you are a big investor, buy it from private sale or pre sale before main ICO.
dont buy it with all your money, safe it. and once hit exchange, buy it more from bounty hunters. usually cheaper price.

Now would be a good time ti buy altcoins, I just saw my folio and most of my coins are red so basically the market now is low at price. If you do have the money to invest then go ahead buy those coins you want for long term hodl.

I think that today is a very good opportunity to buy tokens, because today is very cheap prices, but I just read the information on regulation, so now the market must react very strongly to such news, so we expect prices to fall

The best time to buy will always be the time that we all missed, because it was then the best time to date, but to be honest, I think that people never know when there will be a really good time to buy, because that the market always works differently.

The best time to buy an altcoin is after the ICO and its get listed on an exchange. Most investors who are impatience can't wait till the full development has been fulfilled so will sell it cheaper on exchange. If you buy at this time and wait till the project finish what is outlined in the roadmap, then you can make profit from it.

buying at ICO is very profitable, but very risky too.
wait till it be listed on exchange to buy, but still have wait long time to it really rise
so I think buying at dip is tthe best choice, you can get more than 10% in one day, but that  didn't happen oftenly 

I always miss this moment. but they say that it is better to purchase altcoins after ICO

I think the best time to buy a new altcoin on the ICO stage because the price is still cheap and we can also get bonuses
later when altcoin is listed on the market, the price will probably jump so high and there we can take advantage
then when the price again wastes time it is also a chance to buy back and hold it until the price increases, it could be in the long run and maybe in the near future it will rise again the price

The best time to buy Altcoin is the Dip period because you can purchase your favorite coins at a relatively low rate and hold it for coming pump up period to get more ROI.Always select strong project based Altcoin so that your investment may not go waste.If you invest during ICO stage at that time you can exactly what the coin has to offer you,if you wanna access a coin then it can be well judged during dip period.So i suggest you to buy during dip period.