There will never be a perfect time to invest, more than likely, unless you're extremely lucky, you will buy and experience both dips and peaks. If you can afford to lose your money invest it, if you cant, don't.
At the moment prices will be lower than they have been due to people cashing in to pay for their Xmas shopping. I would expect that, and this is purely speculation, once the banks reopen, after the Xmas break, prices will probably bounce back up. But, that said, they will probably drop down again for new years/around new years due to people over spending when celebrating the date changing on the calender.
theres no perfect time for investment because the price of coins is moving too fast either growth or down.but if we are talking about bitcoin for me everytime is a right time for its designed in long term investment because the first coin of this currencies are always in demand and limited volume.
This days its hard to capitalized a short term investment as the price are unpredictable for the altcoin only bitcoin and those top 5 coins are the reliables for investment but for long term..