if you rinse the yeast, follow the instructions carefully on the sticky on this forum. that way you will get rid of any dead yeast. i use smack packs shipped across the atlantic that are older than 3 months, all the time, they are fine, so don't worry. when you rinse it, work as clean as possible, use boiled water, don't subject them to rapid temperature changes, don't handle the yeast any more than you need to, and you'll be good. you shouldn't need to make a starter from this harvested yeast if you use it pretty soon after harvesting, once it's compacted in the fridge after rinsing, estimate the volume and use mrmalty.com yeast calculator to determine how much to add to your next batch. good luck!