When do I take my first RMD from a pension lump sum rollover to an IRA?

I turned 70 1/2 in 2018.  Subsequently I had a pension from my former employer rolled over to an IRA in 2019.  (The rollover should actually be complete tomorrow.)  When do I need to take my first RMD?  I was told that it would be in 2020 based on the value of the IRA on Dec, 31, 2019.  But I was also told by someone else  that I needed to take an RMD for 2018 since that is the year that I turned 70 1/2.  Which is correct?