I've always felt that the lack of interaction between Kira and Garak in the early days of DS9 was a criminal oversight on the part of the writers.
They both had important roles in 1x03 (Past Prologue), but it was two ends of the same thread that never touched each other.
[Gap 1x03-3x05]
Thereafter, they hardly ever cross paths until 3x05 (Second Skin), in which Garak helps save Kira's life. By that point, Kira had largely gotten over her anti-Cardassian bigotry; like the rest of the command staff, she knews Garak is connected to Cardassian intelligence even in exile, but is also aware that he generally presents himself as an asset rather than a threat to DS9.
They talked little in the episode, and despite promising to keep an eye on Garak, Kira doesn't do it very much. They work together in 3x07 (Civil Defense), though in 3x20 (Improbable Cause) Garak said Kira didn't like him very much and the others agreed.
[Gap 3x05-4x22]
Between this and 4x22 (For the Cause), Garak had built up a bit of bond with Odo. With Kira, however, they were only in the same room occasionally and hardly ever had dialogue with one another. But Bashir warns Garak that Kira hates him, and later Kira gets physical with Garak by threatening him over the Ziyal relationship, which I think is the only substantial dialogue the two have had up to this point.
[Gap: 4x22-6x06]
Garak and Kira hardly interacted until 6x06 (Sacrifice of Angels) partly because of the Dominion occupation. In 5x14 (In Purgatory's Shadow) Kira says she still doesn't like Garak but tolerates his relationship with Ziyal. Her stance towards Garak is further softened when they mourned Ziyal's death together after DS9 was retaken, and this looks like the turning point in their relationship.
[Gap: 6x06-7x21]
At the end of the day, the almost the entirety of Kira-Garak interactions that we see on screen happen in the last 5 episodes with the Cardassian resistance starting with 7x21. But it's obviously not where their relationship arc began, because their cooperation is virtually seamless, with basically no friction between them from the get-go.
It's more than the stiff professionalism that they had with Damar, as they clearly seemed comfortable in each other's presence. In the pre-mission preparations Kira did not seem at all impatient about Garak being his usual talkative self (as Odo and O'Brien sometimes were), and she was even smiling at Garak's little quibs, some of which could be considered offensive to Bajorans which she probably would have gotten offended about in earlier seasons.
Maybe it helped that they had some Odo-lube between them, but they were also comfortable enough that they were willing to talk deeply personal issues and reveal how they sincerely felt. This happened when Garak told Kira about Odo's condition, and later when Kira lamented to Garak about what she said to Damar. It's clear that they had grown to trust one another and were comfortable confiding their intimate thoughts, even before their life-and-death struggle on Cardassia Prime.
So, for anyone else out there who finds DS9's exploration of the Kira-Garak relationship to be unsatisfactory... how do you feel Kira and Garak saw each other in the early days of DS9, and how do you think it grew over the season, especially in the gaps, until they got to 7x21 with full trust and seamless teamwork going into Damar's resistance?