What grammatical term applies to "And then"

I’m helping an Indian buddy out at work by correcting the grammar on something he wrote and as I go I’m putting more thought into grammar so that I can more precisely explain why something is awkward. The sentence he wrote is:

And then, when defining the infrastructure, just add the *endpoint* and *ssl_insecure* values:

I’m correcting it to:

After the user specifies their credentials, they will next need to define the infrastructure. Instead of defining credentials for each endpoint they need only provide the *endpoint* and *ssl_insecure* values.

I’m fixing some grammar and also making it a bit easier to understand (I didn’t originally follow from a technical perspective).

I’d like to be able to provide him a better explanation of why I changed things than, "It sounded weird." To that end what is the name of the grammatical function And then, serves? I know it’s specifying time – do we have a special name for that in English?