If your doing 500mg a week split it into two injections, one Monday, and one Thursday. If your test is 250mg/ml then you'll do 1cc each time. The pins you are using are fine, you could go to a 25g 1.5" if you want. After you draw the oil into the syringe heat it with a hair dryer for 30 seconds so it's more your body temperature. Inject slowly it should take a good 30-45seconds to inject.
Make sure you are using a clean protocal. Always swab the top of your vials with alcohol, and the injection site.
You should draw your oil with a heavier gauge needle and use a thin gauge needle to inject. The reason for changing needles is because you can dull a needle just by going thru the rubber stopper. Never touch the needle with your hands or anything else.
It may take your body a few injections to get use to the BA in the oil. Your injections should over time become less painful.