allowing vial to sit for at least 10 minutes before administering.
asking the pharmacy to dilute the mixture.
Number 2 is correct.
Rolling the vial between the palms of the hands will produce enough heat to aid in the dissolution of the powder. The rolling movement itself will also help dissolve the powder. Shaking the vial could break it, and leaving the vial to sit does not ensure the powder will dissolve. There is no need for the pharmacy to be involved in dissolving the powder.