Thank you all so much for the advice! I really appreciate it.
So what we've decided to do is DH will be at the main gates 30-45 minutes before EE, which shouldn't be a problem because when we're going DL doesn't open until 10. The plan is he will "walk very fast" to Nemo to get in line. Then me, DD4 & DD2 will take the Monorail and meet him in line at Nemo. Hopefully we'll be able to get right on. That would work best for us because I can't imagine walking by myself with 2 young children (without a stroller) all the way from the DLH through DD and then through the gates all the way to Nemo. I can walk fast, but they can't. Hopefully the Monorail will be the way to go for us since it will drop us off right by Nemo. I'll just plan to get to the Monorail line early.
So if anyone doesn't think this is a good idea please let me know. Also, I didn't even know that Nemo was an EE ride until you all informed me that it is. After Nemo we'll hit PP and then Dumbo. Plus I'm hoping DL will be a lot less crowded because school will have already started by then.