Help with changin wet/dry to real sump

[ryshark]

I am in the process of changing out my Toms Rapid Pro PS4 and putting in a real sump and a good skimmer. Today I got my sump 23"x12"x14" (rated for up to 125-gallons) for my 75-gallon tank. I wanted a bigger sump/refugium but I can't even fit the 23" under my tank. I am going to have to cut or carve about an inch off the center brace in the back to get it to fit. I am kind of scared about that. I also got my new overflow box today which is an Eshopps pf800 also rated for up to 125gallons.
I will not be getting my new Octopus NW 150 protein skimmer until Friday via UPS.
My question is this.... should I go ahead and pull out my current Rapids Pro wet/dry and hook up my sump and overflow now and then add the skimmer on Friday? Or is it better to do it all at once on Friday? Thanks for any advice.

 

[ccCapt]

Is the new sump already set up with baffles? The skimmer must sit in a section of the sump where the water level doesn't change. The Octo should sit in about 8" of water.
If you have everything ready, I don't see a problem switching now.

 

[ryshark]

Yeah, I didnt want to mess with building my own sump. It is a preconstructed acrylic sump with two chambers. First chamber is huge and will house my Octopus skimmer (waiting until Friday for delivery) and then there is the up and down baffles with a sponge in between and then there is the next chamber where I will put a return pump.
I also plan on taking the sponge out and filling its spot with live rock rubble. Here is the sump
Berlin Sump BS-1, 23 inch x 12 inch x 14 inch (Saltwater Aquarium Supplies > Filters > Sumps > Complete Units )