Hello Winnie,
I don't believe any of that really matters although I do lie down after "just in case".
To give you an example. Have been pregnant once but sadly miscarried but when I got pregnant I did nothing of that. The position we used was all wrong when it comes to gravity

and went to toilet straight after but I got pregnant!
Now we have been trying for ages and tried lying with feet in the air for 30 min, pillow under my hips etc etc. Not got pregnant since.
If it makes you feel better try to lie down a little after but I would recommend not to over think things.
xx