A published author with rather crude, workmanlike, art skills as a map and technical illustrator for my own series of alternative history/military fiction series, 'Armageddon's Song', and the 'Of Demons & Blue Moons' supernatural thriller series.
Anyone with a little imagination can manage basic photo-manipulation, the software does most of the work, but writers need real artists and photographers for book covers, which is why I am here, of course.
I have a hard and fast rule about initial business emails and notes, I do not wait more than 48 hours for a response from an artist, call it a test of reliability, if you will.
If you are serious about doing business you check your email daily, if you are professional in outlook then you are courteous and you reply, even if it is to decline. In my experience, an artist who takes weeks to answer an offer of a paid job will take months, or never, to produce the work they were being paid for.
Fakes and Flakes need not apply.