In early 2014, I dumped (lump sum) about $120K cash I had been sitting on for 6+ years awaiting a home purchase into the market. I am just sorry I didn't do it sooner. Don't make the same mistake I did. I reserved about $40K for a down payment, just in case, and I know this doesn't make much sense, but that $120K is at an allocation that is much more conservative than the rest of my portfolio, about 60/40 stocks/bonds. That was 3 years ago, and hey, look at us, we still rent. It was certainly an anxiety ridden decision to move it, but like I said, I'm only sorry I waited as long as I did. That $120K is up to $149K today. Again, I repeat, I'm just sorry I waited.
If it makes you more comfortable to DCA in, do that, but don't let another day go by without investing at least part of it.
Give JLcollins' stock series (okay, I admit I haven't finished it) but at least the first few parts, to give yourself a little confidence boost.