The amount of ginger you used depends very much on how the amount of portion you need to distribute. The portion of sweetened vinegar and black vinegar is about 5:1. If you buy Pat Chun, you can ask the sales lady.
For making the ginger vinegar, we make the ginger first. After 2-3 weeks, then add the pig's nuckle. Finally add the eggs. For the eggs, they shouldn't be stay in the vinegar for long, otherwise they will be very hard. But some people like hard eggs.
I only use "at Chun" vinegar as the taste is the best of all. It is good for the mother as well as they add some herbal ingridients in the process which are good for the mother.
In my case, we distribute the vinegar ginger to relatives and friends starting from the 12th day after giving birth. I think the mother can eat also from then (for natural delivery). It takes about 3 weeks to have the ginger soft and delicious (2 weeks can also). So, working back the schedule, you can start making 2 weeks ahead of the due day.
An old lady give me a tip - to take away some of the vinegar of the ginger vinegar and put some fish maw in. The fish maw will then melt into the vinegar. You take one small cup (like 30-50ml) a day. This is very good for replenishing the collegan and helping the bone.