Hi Kevin, welcome aboard.
I don't make mead, I have made spiced beers. I find that a teaspoon of cinnamon blend in five gallons adds light spice to the finished brew. My theory is always go light, too little might disappoint, but too much can ruin your brew. I also read successful recipes for suggestions. Check HBT for mead recipes with plenty of positive feedback. Good luck with it, let us know what you do.
I only use whole spices, not powder. Powder doesn't mix well and often ends up floating on top. For my tastes, one cinnamon stick per gallon in primary and I'll leave them behind when racking to secondary in 2 - 3 weeks. YMMV.
Also Steve Piatz wrote about how you can steep your spices in vodka for 2 weeks and then add it to the mead just before bottling. He suggests taking a small sample and adding some essence and tasting. If you like it simply scale up to the size of your must. It's a bit of s hassle but better than overspicing a good mead
I have seen warnings of overdoing Cinnamon and I did 1 stick crushed to a mead 5 gallon into the secondary melomel. After a few days I sampled and really only got a minimal taste. I will wait to see if there isany change. Perhaps it was because I waited till the secondary to add spices and fruit. I am new at this but so far so good. have 15 gallons in different stages ( 3 carboys.) we shall see.