Sowing annual rye grass-NY October?

Our local garden center advised we sow an an area of garden that is now decent grade fill with annual rye. Also said can be done till end of October. In april next year will have 2-3 inches of topsoil put on it. Located in New York (Putnam) we are concerned about run-off and erosion during winter months, particularly on slopes. Should we even bother with the grass, maybe just spread hay over it. Some comments from prior postings suggest annual rye will leave our lawn looking like hell for a year and its hard to remove, but won't topsoil deal with that. Also wondering if those fake owls sold in gardening shops really work. If they do, then why bother putting hay over the seeds?
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