I have joined many campaigns, and all of them have some similar patterns. Like the price will drop when you can sell. Many people just sell immediately after receiving the reward. Some project prices will keep falling down. But there are still projects that come back strong. I usually hold all rewards for a long time. I join a campaign because I really like it among other campaigns.
If the token has been listed before distribution of reward then you should sell it without worrying for the future because everyone is in Struggle to sell their bitcoin at higher price so if more people sell their coin the price will automatically reduces and if you are waiting for pump then you will see that at the end your coin will possess no value.
If your coin is not listed yet then waiting give a sense because after listing on exchange the value of that token will increases so you can double your profit in such situations. Sometimes holding is necessary and sometimes holding does not give you anything so always think about the situations and try to make a decision according to it because holding will not give you profit all the time.