Welcome, crose.
The age-old question. Either way is acceptable. If you are to ever transport them, leave the cellos on, etc., blah blah blah. Do a search if you like, but it's not that important.
What IS important is that you "season" that humi first. Take a CLEAN sponge and wipe down all the wood with distilled water. It's generally best to let it sit for a few days and do it again and let it sit for a few days more before loading it up. An accurate hygrometer would be nice to see when you're between 65 and 70%, but if your cigars are still in their cellos, they won't lose or gain humidity very quickly (another reason to leave them on) so if it's close you can go ahead and drop 'em in. If you don't season, though the humidor will quickly suck the life out of your sticks.
REMEMBER, better too wet than dry. Once they're dry, you lose prescious oils and they NEVER come back.
Also, if you don't already have it, use 50/50 (PG/H20) solution in your credo. After that, accuracy is not as important, you'll only need your hygrometer as an indicator to falling H20 levels. Then recharge only with H20 for about a year (PG is very slow to evaporate), otherwise your credo will eventually fill with PG and ther'll be no more room for water.
Do a search on PG 50/50 etc. etc. Don't forget to search All Messages not just last week.
Best o' luck.