Dynamic dates


Very new to this program so hopefully this is not a stupid question...

I need to set a sheet up where there are fixed times within a 4 week cycle for certain steps to occur. For instance we can only order a certain pack on Friday of week 1 of any 4 week cycle. Is there a way to set this up so if the predecessor finishes ie monday of week 2 it recognises it has to wait until the following Friday week 1 to complete this next step?

Is there such a thing as specific calender for one step?