Can you buy crypto on a Sunday?

I have made three crypto purchases so far and two of the three have been terrible. I bought ripple and litecoin right before both crashed in a Monday. I know the market is in a bit if a downtrend at the moment, but it seems like FUD comes every Monday lately? Is this just a coincidence? I was going to purchase some Ethereum today, but I am deciding to wait to see if there is a another Monday morning crash. Unless it hits in the 700's again, then I might just have to.