counting days?

JEN • Married 12/31/11 TTC since 1/1/12. We suffered a mc 12/23/14 :( started 2015 we did injections, still BFN, did 1 IUI BFN finally moved to IVF (long lupron protcol) in Sept. BFP! EDD 07/17/16
Hi ladies, I have a stupid question does the ER day count as day 1 for figuring out when ET will be? My ER is scheduled for the 19th and I will have a 5 day transfer and I'm trying to figure out if that would be the 23rd or 24th?