Question: During which stage of the cell cycle is cohesin deposited on the yeast genome?

Context:
In the budding yeast, cohesin is loaded onto the chromosome during the late G1 phase, establishes sister chromatid cohesion concomitant with DNA replication, and dissociates by the telophase. 
Sister chromatid cohesion is mediated by cohesin, but the process of cohesion establishment during S-phase is still enigmatic.
Instead, we find that cohesin stability increases at the time of S-phase in a reaction that can be uncoupled from DNA replication.
By using "single-copy" derivatives of the 2-microm plasmid, we demonstrate that recruitment of cohesin at STB during S phase indeed translates into cohesion between plasmid molecules.
In cells recovering from nocodazole-induced spindle depolymerization and G(2)/M arrest, cohesin-STB association can be established coincident with spindle restoration.
This postreplication recruitment of cohesin is not functional in equipartitioning. 
We have used chromatin immunoprecipitation coupled with microarray analysis (ChIP chip) to produce a genome-wide description of cohesin binding to meiotic and mitotic chromosomes of Saccharomyces cerevisiae.
Cohesin sites are highly conserved in meiosis and mitosis, suggesting that chromosomes share a common underlying structure during different developmental programs.
Cohesin complex acts in the formation and maintenance of sister chromatid cohesion during and after S phase.
 Proteolytic cleavage of cohesin's Sccl subunit at the metaphase to anaphase transition is essential for sister chromatid separation and depends on a conserved protein called separin.
Four of these proteins, Scc1p, Scc3p, Smc1p, and Smc3p, are subunits of a 'Cohesin' complex that binds chromosomes from late G1 until the onset of anaphase.
It is necessary for the establishment of cohesion during DNA replication but not for its maintenance during G2 and M phases.
Here, we show that cohesin destruction in metaphase is sufficient for segregation of much of the budding yeast genome, but not of the long arm of chromosome XII that contains the rDNA repeats.
In this review, we have discussed the life cycle of cohesin during both mitotic and meiotic cell divisions including the structure and architecture of cohesin complex, relevance of cohesin associated proteins, mechanism of cohesin loading onto the chromatin, cohesion establishment and the mechanism of cohesin disassembly during anaphase to separate the sister chromatids.
Cohesin association with G1 chromosomes requires continued activity of the cohesin loader Mis4/Ssl3, suggesting that repeated loading cycles maintain cohesin binding.
Cdc14 phosphatase induces rDNA condensation and resolves cohesin-independent cohesion during budding yeast anaphase.
Cohesins are deposited by a conserved heterodimeric loading complex composed of the Scc2 and Scc4 proteins in Saccharomyces cerevisiae, but how the Scc2/Scc4 deposition complex regulates the spatiotemporal association of cohesin with chromosomes is not understood. We examined Scc2 chromatin association during the cell division cycle and found that the affinity of Scc2 for chromatin increases biphasically during the cell cycle, increasing first transiently in late G1 phase and then again later in G2/M.

Answer: In the budding yeast, cohesin is loaded onto the chromosome during the late G1 phase, establishes sister chromatid cohesion concomitant with DNA replication, and dissociates by the telophase.
In the budding yeast, cohesin is loaded onto the chromosome during the late G1 phase, establishes sister chromatid cohesion concomitant with DNA replication, and dissociates by the telophase. 
Cohesin association with G1 chromosomes requires continued activity of the cohesin loader Mis4/Ssl3, suggesting that repeated loading cycles maintain cohesin binding. In mammalian cells, cohesin binding to chromatin is dynamic in G1, but becomes stabilized during S-phase. Instead, we find that cohesin stability increases at the time of S-phase in a reaction that can be uncoupled from DNA replication. Budding yeast Scc1p/Mcd1p, an essential subunit, is cleaved and dissociates from chromosomes in anaphase, leading to sister chromatid separation.
Exact answer: S-phase