I bought VXC in two installments a month ago, trying to average down, and with impeccable 20/20 hindsight I either wish I'd waited or bought XIC or VCN instead. Some say the Canadian market is oversold, some say that that it will descend further. Who knows ... not me, that's for sure.
Anyway I have other things that are doing way worse. Had my TFSA in a high-interest savings account until August then dumped it into Wealthsimple in August/September plus my January top-up, and I'm down $1767. Woot! Better than my REIT (D.UN) which has lost a whopping $12,500 (36%) in a year and a half, even after factoring in the monthly dividends. I am a "buy and hold" investor and I just sit back and watch all of my stuff tank, tank, tank. In 20 years of investing, with and without advisors, I'm lucky to break even.
Your best bet is to run away as fast as you can from whatever it is I'm buying and holding. I have 80K sitting in a high-interest savings account so when I decide to throw that into the market ... look out!! :)