We let ours out as they arrived yesterday (around 7.30) but we have neighbours who allow their dogs to bark anytime from 6.30 am onwards without anyone trying to quieten them, so we don't feel so bad I would normally say from 8-8.30 once they have had breakfast, but it has been so hot that by 10.30 we are having to keep them on the decking with lots of parasols around so it was nice for them to get out earlier and have a bit longer in the garden!!!