There are many ways to estimate your potential reward.
The best calculator for Solo mining is https://mining.alekseirubin.ru/
However, there is another strategy. You could go to "Miners online" page at the pool of your choice and find the miner with the hashrate which is similar to yours. Look through his statistics to get the idea how much could you mine in 1 hour/12 hours/1 day/1 week/1 month. This method works if only you select the miner who was online for the period of time you are looking for.