I'm no expert but I generally try to have my horse's blood pulled at a similar time of day and generally that time is shortly before or after coming in from her paddock depending on time of year.
I try to be there to make sure that she's not running about before hand but I figure that the testing result will be a reflection of where she's at while living what she knows to be her regular routine. Changing her routine to accommodate a blood pull seems more likely to cause stress for her, imo.
-- Tanna
April 2019, (Yahoo Group member 2008) Langley, BC, Canada