It depends upon your market. If you have a unique service that stands out, you might start earning sales sooner. If you’re offering a service that is just like everyone else in your category, it could take as long as a few months. There really is no one answer to your question.
My advice: Work hard to be unique. People take notice of the more unique and professional services here on Fiverr. Present yourself well, and buyers are more likely to check out your gig listings. Never, ever, ever follow the crowd. Success comes to those who are willing to take a risk and stand out. Leaders get noticed… followers… not so much.