Looking for a little advice if anyone can help

First my oldest,7, very bright, great reader...doing bigger. Started back in July half speed so we wouldn't get behind with the baby coming...he did good, so now we are attempting full speed....he does the work fine, but takes forever...
English and cursive can easily take an hour to hour and half....he will count up how many sentences he has to write and gets upset about the amount. He can do the work and understands it without problem, but basically doesn't want to....so our day gets really behind....I am having to constantly say "do your work"...very frustrating
I have tried a timer ...it goes off and he has nothing done, what do you do?
He seems placed properly.. The only thing in bigger he isn't very interested in is the story time books...started Seabiscuit and he doesn't seem to listen very well.....
My 5 yo is doing little hearts and doing fine....we get through it pretty easily ( usually while his brother is wasting time...)
Now my little girl..turned 3 in sept, wanting to start little hands ....but how do you find enough time in the day?
So, the baby is 4 weeks old and a big boy, so have to nurse him often....every 2 -2 1/2 hrs.
I feel like I am not doing a good job as it seems we just can't get done....
We start early, usually by 8:30, I like to get finished so they can be outside and doing other things....but with my oldest
dragging things out I don't know what to do...
And how do I fit in little hands..? (Did with my second son and loved it, just don't know how to fit it in now)
So, would love any thoughts or suggestions how you make it all work.....
Oh, and if I even have to say, I'm pretty tired of course with the baby....but trying to do what I can!