Prediction? Forget it.
Should you take profit? Wrong question.
It sounds like you are in serious need of a trading plan.
1. Prediction is basically impossible - even trading systems that focus on prediction alter them after them after the fact because its so frequently wrong - looking at you Eliott Wave... Anyone that deals in predictions is going to get destroyed in the stock market - the most damaging form of this would be intraday trading. In general, your predictions will be low accuracy, and executing more trades regularly will compound those mistakes and blow out the account.
2. The question of whether or not you should take profit depends on your money management strategy/trading strategy. Are you high accuracy low gain per trade kinda guy, or a low accuracy high gain once in a while? There's no way you will be high accuracy / high gain per trade or else you would be a zillionaire already and this thread would be irrelevant. You have to figure out which type of money manager you are, and then work from there as to the how much profit is enough to take it from.