The hardest part seems to be knowing exactly when to sell the stock.
Well yes, that's the problem with all stock investing. Reports come out all the time, sometimes even from very smart people with no motivation to lie, about expected earnings for this company, or for that industry. Whether those predictions come true is something you will only find out with time.
What you are considering is using financial information available to you (and equally available to the public) to make investment choices. This is called 'fundamental analysis'; that is, the analysis of the fundamentals of a business and what it should be worth. It forms the basis of how many investment firms decide where to put their money.
In a perfectly 'efficient' market, all information available to the public is immediately factored into the market price for that company's stock. ie: if a bank report states with absolute certainty (through leaked documents) that Coca-Cola is going to announce 10% revenue growth tomorrow, then everyone will immediately buy Coca-Cola stock today, and then tomorrow there would be no impact. Even if PwC is 100% accurate in its predictions, if the rest of the market agrees with them, then the price at the time of IPO would equal the future value of the cashflows, meaning there would be no gain unless results surpassed expectations.
So what you are proposing is to take one sliver of the information available to the public (have you also read all publicly available reports on those businesses and their industries?), and using that to make a high risk investment. Are you going to do better than the investment firms that have teams of researchers and years of experience in the investment world? You can do quite well by picking individual stocks, but you can also lose a lot of money if you do it haphazardly.
Be aware that there is risk in doing any type of investing. There is higher than average risk if you invest in equities ('the stock market'). There is higher risk still, if you pick individual stocks. There is yet even higher risk, if you pick small startup companies.
There are some specific interesting side-elements with your proposal to purchase stock about to have an IPO - those are better dealt with in a separate question if you want more information; search this site for 'IPO' and you should find a good starting point. In short, the company about to go public will hire a firm of analysts who will try to calculate the best price the public will accept for an offering of shares. Stock often goes up after IPO, but not always. Sometimes the company doesn't even fill its full IPO order, adding a new type of risk to a potential investor, that the stock will drop on day 1.
Consider an analogy outside the investing world:
Let's say Auto Trader magazine prints an article that says "all 2015 Honda Civics are worth $15,000 if they have less than 50,000 Miles." Assume you have no particular knowledge about cars. If you read this article, and you see an ad in the paper the next day for a Honda Civic with 40k miles, should you buy it for $14k? The answer is not without more research. And even if you determine enough about cars to find one for $14k that you can reasonably sell for $15k, there's a whole world of mechanics out there who buy and sell cars for a living, and they have an edge both because they can repair the cars themselves to sell for more, and also because they have experience to spot low-offers faster than you. And if you pick a clunker (or a stock that doesn't perform even when everyone expected it would), then you could lose some serious money.
As with buying and selling individual stocks, there is money to be made from car trading, but that money gets made by people who really know what they're doing. People who go in without full information are the ones who lose money in the long run.
