I would put them all under my tongue and let it dissolve there. you won't get as much taste (no tastebuds on the bottom of your tongue, but some will inevitably make it to the top of your tongue). they'd hit quicker.
also, I'm curious, are these DXM only? be careful if it has other stuff in it, like those triple C's kids are doing nowadays and putting themselves in the hospital with. i know it wasn't the DXM that puts them there, but the stuff is just so dirty feeling.
Thats not alot of dxm. You should do some salvia at your peak or smoke weed or do some nitrous. I find those three things bring out the effects of low doses a little more.