Begin with the simple and easy ones first.
3 hours is really a quite less time to get eight homework done. So, better try to make the best use of this time by avoiding any non-homework related activities.
Take someone else's help if possible, to help you in writing.
Make it a point not to narrow eight homework to just 3 hours from next time.
Try sparing enough amount of time to each homework so that you could learn well with no tension.