Weekend part time babysitter

Hi, we're a young family in Roslindale looking for some part-time help with our newborn (now 9 weeks old). One of us will be going back to work soon and works a really varied schedule so our needs will likely vary week to week but we'd guess either 2-3 full days or a few half days would be great. Will need someone who can work a flexible schedule. We're also potentially considering a nanny-share with another family nearby.