Presentism and Infinite Chain of Past Events

[GrandizerII]

Most of you have heard the argument from the theist side that an infinite series of past events cannot be possible because to be infinite in the negative direction would be to not have a beginning at all, no starting point from which you can then trace a line from that point to the present. Yet, here we are experiencing the present. So, according to the theist, there seems to be some logical contradiction going on here.

Eternalism (typically associated with the B-theory of time) has an answer to this, which is that time is not how we intuit it to be. Given eternalism, there is no series of past events occurring in a "time-flowing" manner. Rather, all "past events" still presently exist along with present (and with "future") events. So, it seems to me, that no purportedly impossible tracing of the line from "no beginning" to the present has to occur.

But I was wondering how a presentist atheist would answer to this problem. Assuming time actually does flow, with future eventually becoming present, and present flowing into the past, how do you logically trace a line (as a hypothetical eternal being) from "no beginning" to the present point?

By line, I mean in the loose casual sense of the word, not the strictly mathematical definition of it.