In my opinion, the discounts that I’m seeing are relatively nominal considering that a new iPP has been announced. Were it not for Covid and the concomitant higher demand for iPads with more people working from home and the vast amount of online teaching in schools and colleges/universities, we would have seen such discounts from time to time during the past year. Instead, we rarely saw discounts on new iPPs in stores or even Apple-refurbished iPPs listed on Apple’s site.I'd say right now is the worst time to buy a 2020 iPad unless it is 50% off or more. Your best bet is to wait it out until WWDC and then decide if there is anything that moves the needle for you there since we know the hardware station for the new iPad Pro. If there is anything announced that's interesting you will have more people dumping IPP 2020 models softening the price even more (especially if you don't care for the additions) and if nothing magical comes about the pricing on the used ones will still hover around where they are right now.
I get that there is a debate on how awesome or lackluster this update will be. You can't get hyped on this early, but since this is your first iPad waiting about another month seems prudent to me.
I am convinced Apple didn't decide to disclose RAM on an iPad and add a historically abnormal amount of RAM to it by accident. I think there will be some serious surprises at WWDC that may make 2020 iPads really tank in value. Especially since they are pretty much the same as the 2018 with super minor tweaks.
I’m going to hold steady with my 10.5” iPP for a little while longer.