New 3.0 install with Xcart Live still

I currently have my site running, older version of xcart. I mess around previously with opencart, but did not finish the change over. I am getting lots of errors now with xcart so I plan on finishing the site ASAP, but at this point it looks best to do a clean install of 3.0.x . Originally when I was messing around with it, I just installed everything into a sub folder on my server and worked on the site in maintence mode.

My question at this point, what is the correct procedure to install opencart (I know how to do the basic install, no need to explain that), configure it and then move it over when done while the current site stays live and functional. I cannot afford to have my site off for more than a day or two...is it best to just do the subdirectory again and then move it? Or do I need to not move it and just delete the old site when ready? What changes do I need to make to the new site to turn it on? Used to have a webguy who did all this, but he no longer does web stuff, so I am on my own and bit confused on the proper setup and my hosting company has provided no answer.

Thanks

Later Eddie

Typical procedure is to setup OC in a subfolder, then move it up when it's done. If you want to avoid loosing any orders you can do it overnight when web traffic is lower.