There is no evidence to suggest getting up straight away after the procedure has any more positive effect to lying still for 20 minutes. This will be a personal choice for you. As your bladder will be full for the procedure you may be desperate to pass water. This is fine to do straight after your IUI.
What should I do after the IUI?
From the moment you have your IUI you should treat it that you are pregnant avoiding foods such as pate and soft cheese. Apart from that you can carry on as normal.
Further Reading:
What does the IUI procedure involve?
When should I have IUI?
Is IUI painful?
How & when is sperm collected for IUI?
What are the success rates for IUI?
Is it safe to do IUI at home?
What does washed sperm mean?
What is DIUI?
Related Articles:
Home Insemination
IVF
Natural Insemination