Tips for New User from tableau Background?

thank you for the YouTube tutorial links....

I'm really asking if anyone like me has had to switch from one to the other and has any tips to keep in mind and ease the transition.  I can create a database to work from, but I'm lost when it comes to DAX language and calculations, scripts, etc.  I could run an online search of a tutorial on how to do this or that particular thing, yes, but it's even more confusing to me as in why it's done this way.  For example, I help with logistics and need the workweek to start monday, end friday- not count any weekends into calculations.  Our business doesn't work at all on weekends, but to count a load being ready on friday to being assigned on Monday, should be one day, not three.  I've seen tutorials creating entire extra table sets and joining them, using DAX and all this, and I can't wrap my head around how much extra work it looks like we're doing when tableau and excel can basically define a workday and workweek much simpler.  Part of me is scared because I don't want to lose the knowledge I've gained in another program by overwriting it with this, and the other isn't quite making a connection to more easily transition.