Since you are not in flower yet this is the time frame.
cutting to good roots 2 weeks
flip to flower 2 weeks
flowering 8 weeks
12 weeks from now is Nov 5th. and first frost there is Oct 7th and that is 0 veg days. Outdoor cloning is out of the question. Not to mention you will need light to stop the clone from flowering. Topping will delay the flowering and in Denver you don't have enough season left to delay. Average first frost is 8 weeks away.
If you want to save the genetics you would have to set up an indoor grow. I've taken cuttings from lower branches the week before harvest to save irreplaceable land strain genetics. You have time but the longer you wait, the harder it gets.