HELP!!! How do I do this???

Ok I will be 18 weeks on this Friday... I am a FTM... how may weeks along is good for having a baby shower... we find out the gender on Feb 7th and I'll be 19+6 that day, so almost 20 weeks..

I want time for my guests to purchase gifts but I also know that we will need time AFTER the baby shower to return or exchange items if need be...AS WELL AS setting up for baby and to also be safe in case baby comes early... ugh so close yet so far away and so much planning to do!!