I soak each sinew bundle in water for about 5 minutes prior to dunking in the hide glue. That gets things nice and limber. I found that too much time in the warm glue pot can make the sinew start to curl up and it gets really hard to use. That's why I pre-soak and then just dunk a few times in the glue.
Also, the finer you can get your sinew threads, the quicker they hydrate and the easier they are to lay on the bow.
I'm working on one now, and it must be 100#. I'm shooting for around 50#, so I have a lot of work to do. The sinew has cured for a few weeks in air, then a couple days in a hot box. I can barely get it to brace height. I think this one is going to be a screamer if it doesn't break me before I get it tillered.