[patio11]

You worked on two days, you charge two days, as agreed in the contract.

In the unlikely event that your client is unhappy with this result, you assist them in batching their work together to be scheduled more efficiently, but -- and this is very important -- you don't second guess their business decisions like wanting that original work to be started on Tuesday. At many places that is a totally reasonable thing to want which they are happy to pay for and you owe no apology or explanation for charging as agreed.