You can set a signing order in the SEND DOCUMENT FOR SIGNING dialog. To do this, select the Set signing order option.
Each signer will be automatically assigned a number. Immediately after clicking on SEND DOCUMENT, your document will be sent to signer number 1. After this, signer 1 will sign and submit it, it will be sent to the number 2, and so on.
You can also set a specific order you want the sequence to follow by using the boxes on the far left. In the following screenshot, you can see a workflow where your document will be sent first to signer 1 and signer 2, and only when both of them will sign it, it will be sent to signer 3, etc.