Unless there is an unusual urgency or deadline, preparation of the best possible utility patent application, where no prior provisional application has been filed, for the fee estimated, usually requires about 6 to 12 weeks, providing the client cooperates in providing promptly any information which is needed.
When the application has been filed, the client has a “patent pending”, and may so mark goods containing the invention. Also, many clients, having filed their application, choose at this time to seek licensees, seek capital, do marketing, etc.
After the filing of the application, the Patent Office, normally within about eight to fifteen months after filing, mails an Office Action, to which a response is required within an additional three months. It is all explained in details on https://www.advfn.com/newspaper/advfnnews/50958/let-inventhelp-assist-with-your-invention-idea.
Even for an application on which a patent is allowed and issued, the prosecution period is likely to be at least two years; and the additional cost (over the application costs) to the inventor, including Office Action responses, the Patent Office issue fee as well as legal fees, through issuance, is likely to be about the same amount as the fee for originally filing the application.
Should the Patent Office mail a “final” rejection of the patent application, there are several courses of action still open (depending on the particular facts), such as an appeal, or the re-filing of the application in the same or an improved form, etc. Of course, the client, at every point in the prosecution, is provided with cost estimates of the next required step, and the client will make the business decision whether or not to proceed.
After issuance of a utility patent, increasing maintenance fees are due at 3 ½ years, 7 ½ years, and 11 ½ years as described in https://www.tmcnet.com/topics/articles/2019/05/23/442268-turn-idea-into-new-product-with-assistance-from.htm. The penalty for non-payment is early termination of the patent rights (now lasting 20 years from the date the application is filed).