I want a second opinion!
The danger with these batteries (various Ion types) is that if they get overly discharged they can malfunction. Now it probably depends on the battery manufacturer, but I've heard they store them at about 1/2 charge or so. IDK if that 1/2 the max volts, or what. But that's why they tell you to charge them 1st....so you don't over discharge them 1st, then try to charge them.
I guess you could use your multi-meter, or a PV that shows
battery voltage to check em.
I'd charge em 1st. But then again, I have a charger
P.S. While we're on the topic, and you're using IMR and are new to it and external chargers....Have you researched how not to over-discharge them? Does you PV cut out at some low-charg limit? (I assume so, but I'd check). Some don't let their IMR batteries go below 3.3 volts. Some are even pickier.
Me? Since I used stacked protected stuff I let the protection PCB worry about it if I don't charge em earlier. May not be a good idea, but my PV doesn't sense battery charge.