Quick CO2 Question-set up before plants?

Good plan to not rush yourself! That mindset can payoff very well in this hobby.

When I got into co2 last year it couldn't have gone much worse for me. It started when my fluval 206 starting leaking in 3 spots (new aquastop valve fixed 2 and lubing the big o-ring fixed the other). Then my gla regulator went on back order for about a month then arrived with a faulty diaphragm. I found that out about 4 weeks into high light, 8 hour photoperiod, and 5bps. A 2 week hiatus from co2 to return the regulator fixed that issue but my tank never seemed to rebound from the lack of co2 for 2 weeks. Bba along with green dust took over and by the time I got it under control (roughly 6-7 months) my plants were nearly non existent and then my co2 cylinder ran out of gas. My tank looked great for the first month or so though. My reg and cylinder are now in my closet waiting to be put back to use on my 3gallon bowfront in a few months.

The only thing you would be doing is wasting 2 days worth of gas but that's really a negligible amount of co2 for any standard size cylinder. However, you may come across a problem that can be solved by the time you setup your tank. Making sure your gear is working properly is a good thing to do and it can save a lot of time, cash, and frustration in the future.