Just about any gel or powder is good! some people don't even bother using anything,and also to answer your other question,NO it's not to late to take clones from your plant,infact you can take clones at any time you want,I often took clones from a flowered plant,sniped the bud away and just left the leaves,,,and clone the cutting, that I just finshed taking a sample bud from!..

But keep in mind when taking cuttings (clones) when plant is in flowering is a much harder time getting the clones to root!,the further into the flower cycle the harder it is to get the roots to get really going...

True story: One time I had a certain strain that I loved and sold a bunch of clone cuttings from my Mother plant to a few growers I knew,and I loved the strain so much it was a great smoke! so I decided to get some decent bud from her in 8 weeks or so through her into flowering after about the 5 week into flowering,I cut a bunch of clones from her in hopes of keeping the strain alive,in hopes of getting another mother to replace her from one of her own clones, keep in mind she was now heavy in to starting to show bud,what ended up happening was that none of the clones took! I was horrified lol,they got moldy real quick and I was taking the lid off the humidity dome every 5 hours or so,and she wasn'r soaked either,but yet the clones sat in the medium for three weeks still no rooting,just mole lol.......but this story has a happy ending,I let my mother plant finish up shy a week from finish,cut all the buds of and put the mother back into veg and managed to save one of myfaviorite strains...........................note:taking cuttings while plant is deep into flowering is possible,but the effort to get those babys to root is a much harder task then say cutting in veg state...............