ETF OR STOCK INVESTMENT?
No, this is not the best time since everything is down. The fact that the market is down does not make it any better or worse than any other time. There is a old saying "Never try to catch a falling knife" which some people use to time trades, never buying when an ETF or a stock that is falling. Instead they wait until it starts going up again. Like most old sayings it is somewhat vague (How much does it have to go up before you decide it has stopped falling?) and works well sometimes and leads to poor decisions at other times. Unless you are making very short term. momentum based, trades trading based on past changes in prices is usually not a very good strategy. Timing purchases and sales is notoriously difficult and relatively ineffective. Instead you want to look more at fundamentals and make trades based on those fundamentals, particularly if you are looking at individual stocks instead of broad based ETFs. If you do not want to take the time and effort required to learn about and research fundamentals, the best course of action is buying broad based ETFs and holding them for long time periods. Since the sooner you buy the longer you can hold, "now" is usually the best time to make an investment in the market. The more volatile the market is the more risk is involved in investments. Risk should not be considered all bad. It is true you can lose more money in a volatile market, but you can also make more money. The market is still relatively volatile so be prepared for prepared for larger than average gains or losses. If I were looking to get into the market for the first time I would probably invest 50% to 60% of my long-term investment funds into a broad based ETF initially and increase my investment regularly, probably quarterly or annually. Because the market volatility I would keep more cash in savings accounts or money market accounts than I normally would to reduce the volatility of my portfolio.
An ETF is stocks (i.e., S&P 500) and provides diversification. Unless you are investing a significant amount of money (i.e. $20,000+) you can't get diversified enough to provide a safety valve for your investment. The bigger question should be what type of ETF (or mutual fund) should you go for (growth, value, international, developing country, small cap, etc.). If you are looking long term, look into making an initial investment and then monthly investments (look up the term dollar cost averaging).