IF-2016: Are the ‘Copies of Ethics Approvals’ are due at the proposal stage. If they are due and provided, some of the documents are not available, what timeline for future submission would be acceptable?

They are not due at proposal stage. In the ethics self-assessment guide you will find the text: “Your proposal must include the information indicated in the ethics issues checklist and any of the documents that are already available. ( For documents that are not yet available, provide an approximate timeline for their submission.)”
http://ec.europa.eu/research/participants/docs/h2020-funding-guide/cross-cutting-issues/ethics_en.htm
http://ec.europa.eu/research/participants/data/ref/h2020/grants_manual/hi/ethics/h2020_hi_ethics-self-assess_en.pdf