Yes, as long as it's visible. Most of us use holsters that are on the OUTSIDE of the belt (OWB = OutsideWaistBand)...if for no other reason it's just more comfortable, as IWB (InsideWaistBand) holsters -- which are usually meant for CC -- aren't so much comfort-wise. But if a IWB holster is good for you, then go with it.
If you are new to OCing though, you may want to get a good "OC holster" to add to your collection and reserve the IWB holster you already have for CCing only. Try an OC holster and see if it's more comfortable. And if you can access your gun faster/more easily.
If you ALSO get a Colorado CC permit, then it doesn't matter if your shirt/jacket sometimes covers your gun or not: With the CC permit, you're "covered" either way re: being legal. All the OCers I have met here in CO also have CC permits...one guy has 4-5 of them for other states, too! We just never use our CC permits HERE in CO since we almost always OC.*
[See this OCDO thread for a FREE CC class: http://forum.opencarry.org/forums/s...Offering-free-Colorado-Conceal-Carry-classes]
As for me, I ONLY carry OC, never CC here in CO.
[Besides, I can't FIND my CC holster: Last time I saw it was back in Galveston when I was moving (May 2013), so it must be in a box somewhere -- hate to buy a new one!]
I don't know what county you're in, but you might want to go and apply for a CC permit so you'll have it just in case you need it.
Also, a CC permit helps if you visit another state that does not allow OC...if they recognize CO's CC permit (reciprocity) then you can CC there. This works for me when I visit Texas. As for NM, it's business as usual so I OC there exclusively...but in case I DO need to CC in NM, I DO have my CO CC permit with me.
* we only have "D&E" (Desensitize & Educate) going on out there if we OC
...if one CCs, since no one (the public) sees the gun, there is no D&E possible.
Consequently, only OCers can D&E...so we need LOTS MORE people OCing!