A question you really need to ask yourself (and him as well) is if he can reasonably KNOW when he's going to be able to leave for the day in order to give you the heads-up you want.
For example - my family has a housecleaning business. We've had it since the early 90s, I grew up working in the family business. We don't have set hours, because we're the bosses/owners and if something goes amiss, it's on us. Also because it's housecleaning, our employees/teams don't all arrive back at the office/aren't all done with their days at the same time each day. Sometimes we stay at the office until 7pm waiting for the last teams to get in (traffic affects this as well.) If a client calls in with a request as we're getting ready to lock up, we are going to be there longer. So I could never tell you an exact time when I'd be getting home, and even if I told you one day "looks like it'll be around 5", there are a million things that could happen that could delay me at the office (especially since it's a family business, I can't just pass it off to a co-worker) that would mean I wouldn't be able to make that 5pm time I'd originally promised.
I'm not saying your DH is in the same kind of situation as I don't know what kind of work he does or what his self-employment is - but that's how it is for me. It was hard for me to hang out with my friends when I was in my 20s, because most of them had jobs that were regular 9-5 jobs and they would absolutely be off work at 5 and able to hang out. I would try to arrange to be done with work at the same time on days we planned to hang out, but a lot of times things would come up (e.g., one of our fleet cars would break down and I'd need to go out with the jumper cables, etc.) A lot of my friends got understandably frustrated and my friendships faded.
It was the same with my boyfriend - we'd try to meet for dinner or have a date, and I could never be sure I'd be able to get out of work on time. Dates got cancelled quite often. I know it can be really frustrating for the person on the receiving end.
I'd ask your DH if that's the situation - is it difficult for him to give you a heads-up on when he'll be home due to the unstable nature of whatever his job is? If that's the case, you need to firmly set down some boundaries to let him know that you and baby CANNOT "just wait" for him to get home whenever he is going to get home - if you need to run errands at xyz time because baby eats at abc time, you can't wait for DH to come home way past xyz time just because he WANTS to run the errands with you.