My rabbit has a swollen eye, what can I do before the vet opens?

Thank you for the picture, and I hope that we can get Sophie feeling better soon! I like your idea of taking her into the vet on Monday when they open, as swollen eyes can be painful, and eye injuries can be serious.
Until then, I would recommend keeping the area clean, and trying to keep hair from going into the eye, as it can scratch the cornea (front of the eye). You can also apply an over the counter tear gel (such as GenTeal or Optixcare) 3-4 times daily. Please try to get one of these two brands, and make sure they are just the year gel without any additives in them. This will help to keep the eye lubricated until Monday.
Please do not apply any other medications to the eye, and don’t give any human medications to your rabbit, as many of them are harmful to them.
If you feel that the eye is worsening tonight or tomorrow, I would recommend trying to find an emergency clinic that see rabbits.