I don't think so if they have an specific time to sell alt coins.besides if you have a good profits on that altcoins now or tommorow or the other day.you can sell it.you said you don't want to hodl for long term then sell it at a good price.you better to get target price to have good profit and that's enough I think.
I think for me the best time to sell it is the time after the dump it will took 6 months to a year before you successfully earn the good value of the coin you are holding, you can still sell coin during the dump but you can lose most of the value of the coin.