In the English Grammar Profile, B2 point 8 in the category of DISCOURSE MARKERS in writing is defined as a:
range of phrases as discourse markers to open and close texts and point to conclusions, often in formal contexts.
From the examples in the EGP searched in iWeb:
In the English Vocabulary Profile:
‘to begin with’ is
B1 ‘at the start of a situation’ or
B2 ‘used to give the first important reason for something’
The most common collocates up to 4 spaces to the right: