They should open on the first day, no later than the second and seldom on the third. If so, there's a reason. Tank conditions/parameters greatly dictate how soon expansion transpires along with shipping conditions if indeed they were shipped, and not relying on the 1 or 2 day rule. New arrivals in a new system should be placed low to med, alone/solitary, hit by current to remove any stress related slime/expulsion, and always under actinics only on the first day. It has worked consistently for me for many many years now.
Mucho
BTW, dip you dip them?