It is quick, at this age all they do it pretty much eat and sleep. The eat can take quite a lot of energy for them and is actually quite an active activity time, even if it doesn't seem so to us.
At this age he may be able to manage a little longer between sleeps now (the average A time being about 1hr15/20 mins) but if you're getting those good long naps don't worry about changing things too soon or too quickly.
It is fine to do feed and then sleep at BT, perhaps just do a nappy change and put him down for the night.
Hope that helps x