The small bakery had struggled to attract customers throughout its first winter in business. ______, a local food blogger's glowing review…

The passage describes a straightforward sequence in time: a difficult first winter, followed by a specific event that changed the bakery's fortunes. Then correctly signals this simple temporal progression. Namely introduces a specific example of something just named, which doesn't fit this shift in circumstance. Regardless would suggest the review's effect happened without connection to the earlier struggle, but the passage frames the review as the very thing that resolved that struggle. Specifically would frame the second sentence as elaborating on the first's claim, not describing a new, later event.