Cat introduction with new kitten

So far we have swapped scents, which was going well so the other night i let my older cat -coal- in the room while the kitten -jasper- slept. He sniffed around a lot looking for jasper so i picked him up and showed him jasper sleeping and he growled a bit but stayed and watched him for a while. I loved on him and then had him leave after about 10 minutes. The last two nights I have cracked the door for Coal to watch Jasper and he will sit and watch for a while but starts growling when Jasper gets toooo close. Jasper is very curious but listens to Coal and backs off. Tonight Coal let him get fairly close before he hissed and ran off, he kept coming back to my door tho to watch him again.

Im overall just curious to know if this is going well or if I should take a step back.

I should add it took Coal only about 3-5 days to warm up to our puppy when we got her a year ago and they're super close now. The dogs love Jasper already as well.