Hi Willow, I've been through it lots of times now. Timescales vary, I've had intros range from 6 weeks to 7 days. It depends a lot on the age of the children and how prepared they are. As a (very) general rule my babies have tended to move in 7 days whilst older children (oldest was 7) are around 2 weeks.
Be prepared to be VERY tired even though you're not doing much more than you usually would. It's emotionally draining, and making conversation with strangers for 12 hours a day is not easy. Plus there's all the baggage of preparing yourself to let the children move on.
Be prepared for your foster children to be little angels during the day, then release all their emotion at night once new parents have left.
Usually half the intros will be at yours, and the second half at the children's new house. Second half is generally easier for me (as you obviously have left child care to do) but much more emotionally challenging as it becomes real that they're actually going...
I don't think you ever do "get over it", you just "get on with it". I don't have a break between placements if I can help it. Can't afford it, and also the house is so quiet it just leaves time to brood.
Do you have a buddy system in your area? Lots of FCs will know exactly what you're going through and be able to offer support locally. Otherwise, feel free to PM me.