I never had a sling but while Flynn was little I would wear him in a baby bjorn (I could sit down easily with him in it) and once he had fallen asleep I could easily remove the front and pop him down into the bassinet. It meant that I was more able to do things around the house, not that I necessarily did tho!!! I wrapped him too until he was about 5 or 6mths old. Maybe you could try wrapping him with one arm out?
He is still tiny and will not be getting into any habits until at least 3 or 4mths.
HTH