In order to get accurate P&L charts through earnings, you need to model the one-day volatility crush associated with earnings. Unfortunately, most options software (including what brokers provide) is not equipped to accurately model this volatility. You generally can't do it yourself on their platform even if you decrease the IV, because it decreases it across all options equally. If you broker lets you model changes in IV for different option chains, you might be able to do it, but then you need to know how to model it, which is itself a challenge.
There is some software (OptionVue and the spreadsheet that's included with Exploiting Earnings Volatility are the two I know of) that does model the IV collapse with reasonable accuracy, but even then it is difficult to come up with profitable options trades.
In order to employ earnings trading as a profitable strategy, you need some kind of edge over the market. You either need to be better than the market at predicting volatility (size of move), direction of move, or at finding pricing discrepancies within the option chain. I've been working on it for several months now. I do think it's possible, but neither easy nor for the feint of heart.