Cryptocurrency is definitely worth investing in. But nobody will tell you what is the best time to enter the market. The price is attractively low right now. However, Id suggest to put half of your money and wait for a clear sign of an uptrend. There are many bullish predictions for 2019. The growth is not far off, and if you are looking where to buy bitcoin or other cryptocurrencies, try CEX. This exchange allows depositing USD or EUR (
https://cex.io/btc-eur) with cards or via fee-free wire transfers.
I agree with you, we need to wait for the moment when the market will turn around and show full growth, and until that moment it is necessary to do with minimal investments, do not take risks.