Hi Rhubio and welcome to GoY which plant are you asking about?

Sorry, grapevine

yes but not to hard they tend to bleed sometimes.otherwise nov-dec is the time to shorten the side shoots.
although having said that you will need to remove the excess leaves so the grapes will ripen
.i did prune mine in the summer but not into the older stems only the new soft wild growth

Rubio you will need to keep pruning the new growth back or the vine will put all its energy into growing leaves and stems and none into growing fruit. Grape vines fruit on old wood so you can keep the new growth cut well back and then prune properly in the late autumn early winter.