Hi Freya,
I expressed and stored colostrum from 37weeks. I was advised not to do it before them because it can stimulate labor.
Buy some 3ml syringes from the chemist. I used 1 for the whole day.
I found a wheat bag or warm shower good to warm my breasts first before expressing.
I expressed up to 4 times a day for 10-15 minutes at a time. Some sessions I got 3ml some .5ml.
Massage your breast, hold the syringe tip to your nipple, squeeze behind your areola and pull the plunger of the syringe to suck up the colostrum. You will need to frequently hold the syringe upright and gently push the syringe plunger to get the excess air of the syringe.
Put 1 days worth of syringes in a Mini snap lock bag with your name , the date and amount of colostrum.
I would recommend keeping a tally so you know how much of a stash you have when you go into labor.
If you decide to take some in when you go into labor, put it in a chiller bag with a couple of ice packs. Colostrum can go missing in hospitals if its not kept with you, it's liquid gold.
I didn't end up using it in hospital but used it for DD when she has colds... It worked a treat.
Good luck, I hope my experience helps you to get the hang of it fast.