I have got two bags of coffee - trying to save the shipping costs
1) a medium roast washed coffee from Congo 2) lighter roast natural Ethiopian both from Happy Mug roasters ( shout out to them they have really good coffees bang for buck )
These coffees were roasted on 8th of March, I am thinking should I freeze the Ethiopian coffee while start using the Congo coffee. But then I haven't frozen coffee before and I don't want to waste coffee because of my mistake.
So the question to you all learned folks is, usually lighter roasts need a week and half of rest time. So should i just start with the medium roast coffee and by the time i will get close to finish these beans the Ethiopian would be ready to be used at its peak after almost 1.5 or 2 weeks of resting. Or I should just throw the bag with one way valve into freezer take it out after i am done with medium roast coffee and then defrost whole night and start with that bag as usual without refreezing it.

There's a few videos about this on YouTube, but I'd say if you're going to consume your first bag within 2-3 weeks, I wouldn't bother freezing the second bag. Like you said, it usually takes 1-1.5 weeks for the beans to settle. The aging process starts to speed up once you open a bag, but as long as it remains closed it's alright.

Somehow I believe to taste beans age a lot quicker after they've been frozen for a while. It's fine/better the first few days out of the freezer, but drops off a lot quicker than those who haven't been frozen. For smaller quantities that's alright, but not when you buy kilo bags.

I concur that the beans seem to drop off a cliff much sooner if they have been frozen and then brought out for consumption. I recently froze beans for the first time. I usually buy 12/16oz bags that have been roasted within 1-3 days of purchase, so freshness isn't an issue, but have started buying 2lb bags to save on shipping etc. When I received my latest 2lb bag (Saka* Dark Roast), I froze 1/2 in a filled up large mason jar. The other 1/2 I kept in an airtight canister for daily use. The first 1/2 started dropping off a cliff right at the end of the batch (after 10-14 days). I was happy that the 2nd 1/2 tasted fresh after I had taken them out of the freezer and let get up to room temperature. However, they fell off a cliff about halfway through the batch (4-5 days). As a result, I have ordered a bunch of smaller mason jars that I will fill up with 4-5 days of coffee at a time for freezing. If freezing, make sure to allow them to get back to room temperature before opening, to avoid condensation on the beans.

You can also do a search for Freezing on this site. There is lots of great advice (as usual).

*Although I said that I usually get very fresh beans, the Saka beans were already about 2 weeks post roast when I got them, so that should also be factored in.

There really isn't any reason to thaw frozen beans. Just grind them straight from the freezer.
And the associated Nature article he links to.

You could also review the 23 other threads asking about freezing coffee here.

At your service:
Frozen Coffee Storage Calculator
I've been freezing coffee since alt-coffee. I'd been doing for more than a decade when cobbled up the calculator.

macal425 wrote:I concur that the beans seem to drop off a cliff much sooner if they have been frozen

Beans only drop off faster if they been improperly frozen or after a very, very long time. IIRC, CannonFodder found some after many months and it brewed up just fine.

I purchase five pounds at a time. I don't adjust grind or dose by more than 0.1g over the five weeks I consume the coffee.