This will be short, but sweet. I would set up all your mechanical filtration and fill the tank with plain tap water and run the system for 24hrs., which will notify you of any leaks before you put actual time in setting up the system. While the tank is running on plain water I would start mixing saltwater in a separate container. If you haven't purchased a substrate, I prefer aragonite-based. This should be rinsed well, but there will be residual cloudiness regardless. After 24hrs, if all is well and there are no problems with the tank's plumbing or structure, drain and add your substrate. You can either purchase cured or uncured live rock. If uncured is used it will help begin your cycle for you; otherwise, a piece if shrimp is commonly used or other Ammonia source. You can either add the live rock first and fill the tank with water or just the opposite, but I find it easier to structure the rockwork without water and then fill. Your cycle will take anywhere from 14-30days before you notice any parameter stabilization. Your tang will need to be quarantined ahead of time for 30 days and I would perform hyposalinity (you can 'Search' these terms). A tang will last 2-3 months just fine, if small, under 4" as long as you plan to upgrade soon and don't cheat your way through a cycle (impatience). In all honesty, if you plan to upgrade in 2 months then is it really worth the time and stress of the animal if it's too be moved? What is another couple months wait if it means a better display for the animal? Anyways, if you don't plan to upgrade to at least a 75g then I wouldn't purchase a tang.