Building ... When to sell?

We have just signed a building contract, and are in the process of applying for finance. We will be able to keep our current home until the new house is finished, but we really don't want to keep either house empty for an extended period.

When did people start thinking about selling their current home? As the build hasn't actually started yet, we have no idea of a SET finish date, we have been promised by Christmas ... but the contract does state longer than that. We don't want to be in the position of selling our current for nothing, because the new home is ready.

What if you sold your home with a 30-60-90 day settlement,
with possible 1-2 month back-rental attatched thereafter if needed ( a clause in the contract).
Many people do it .

We are going through something similar. We sold our current house and am renting for a year while the build is happening. Reasons are:

- we know what our build budget is without relying on selling our house at a certain price
- no rush to sell current house
- no need to accept "lowball" offers
- will the housing market be better or worse in a year?
- renting is pretty easy. . Get a place with 1 or 2 weeks notice and vacate with 4 weeks notice

Also I forgot to say ... With the lease back option that may work if buyer is an investor.

However if they are buying a place to live in it will mean they need to pay capital gains tax when they sell. If I were buying to live in a place I would never lease back.