What kind of daycare provider will she be going to? How many hours a day? Part-time? Full-time? I am an inhome daycare provider and babies who do not take bottles are very very difficult. To be honest with you, I think you need to spend these three weeks getting your baby to take a bottle so that she will be prepared for daycare. I am totally for breastfeeding and am currently breastfeeding and bf my other 2 children for a year. I also had a my own baby who refused bottles, so I understand how difficult this is.
However, when breastfeeding interferes with how your baby is going to settle into daycare, I think that you need to make some changes. If your baby is going to daycare full-time and all day, she is going to need to have milk. Your baby is 8 months old and has been refusing a bottle her entire life. Offering once a day for the next 3 weeks is not going to make her take the bottle. I think you are going to need to completely stop nursing her for the next 3 weeks. Only offer the bottle until she takes it. Once she is comfortable with the bottle, then start nursing again.
I know other people who will say it doesn't matter if the baby eats at daycare. Sometimes these babies will reverse cycle and just nurse a lot in the evening. This may work if you have the right childcare--like grandma watching the baby. However, if you have a baby in a group daycare setting, it is very very hard on a provider to have a baby who won't eat. Even with reverse cycling, the baby does want milk during the day. The babies that I have had who wouldn't take a bottle were very crabby an unhappy--they were hungry. I think it is important to teach the baby to take a bottle if you are going to be away for an extended period on a regular baby--for the baby and the provider.