Assuming that a penny stock you're interested in trades on a respectable exchange, the company must regularly and honestly report its financial results.
Companies release their financial results by quarter (three-month period), and the four quarters make up the annual results. If a company has a fiscal year ending on April 30, then the quarterly results will include results of operations as follows: the first quarter (usually referred to as Q1) is May to July; Q2 is August to October; Q3 is November to January; Q4 is February to April. As soon as a company has its Q4 results, it can also release its annual report for the full fiscal year.
Stock exchanges impose a reporting deadline for quarterly and annual results, and the listed companies must adhere to this timely reporting requirement for their stock to remain in good standing. Financial results are generally released about two months after the end of each quarter, and within four months after the end of the fiscal year. This delay gives companies time to compile and review their results, provide official versions to the stock exchange, and publicly release the details.
Reported financial results become public data, and as such you can access the information as soon as it is released. The information is available directly from the companies, as well as through the major financial websites.