mail order questions

I am new to starting my own business. in a few weeks I will be taking
orders for  product I created. if a person mails in thier order do
they expect it to be shipped out the next day or are 3,4 week lead
times are still acceptable. If a person see an interesting ad, they go
to the web site, and I tell them These thing are created in my
bathromm or garage, would that hurt my credibility. Do all website
visitors expect every small business to put on corporate airs?