Might not be useful advice, but the pharmacist volunteered to handle that very first shot while explaining every step along the way. Skip that intervention and there'd probably have been hours spent frozen, pen in hand, unable to follow through. Eventually a small personal ritual got built around it, some music playing plus breathing exercises. Now it's over before it even registers. On the nausea front, an over-the-counter motion sickness pill sometimes goes down beforehand, if that brings peace of mind, no harm trying it. Otherwise a walk with headphones in afterward keeps the mind off any queasy feeling that might creep up.
Best of luck with this.