welcome to your new addiction =)
Totally agree the flow will not affect your cycle at all.
You should be adding an ammonia source though if you haven't been doing it. You need to feed the nitrogen cycle in order for it to build to levels to support life. If your not ghost feeding, using shrimp, bottled bacteria or straight ammonia it's prolonging your cycle and once fish are introduced you will have another mini or possibly full blown cycle. I'm sure the rock had something on it but you should he making the bacteria work their Butts off to make your life easier down the line.
I think you should add some flow to the tank also just to manage things settling out and dead spots.. Jebaos are great inexpensive pumps to hold you over until you get the ecotech fwiw. Imo there is no substitute for the mp's looks wise and the cool factor that's why I have so many =) nothing wrong with cheap koralia's though either. You can go to your local forum and put a want to buy ad up to purchase things from local Reefers just don't try to sell or trade and your all good.
Do you have a shut off kit on your rodi? Best investment ever because you will leave it on and that can be avoided for less than $30.
Good luck tank looks great so far and you are doing it all right so far by learning the most important part of reefing, patience =).