Hi Alex,
Would it be an option for you to throttle your snapmirror transfer to a much lower throughput during business hours then increase it to unlimited throughput after hours? Rather than abort the transfer you could limit it 1KB during business hours to keep the transfer extremely slow during the day then use all available bandwidth post business hours. See the "-MaxTransferSize" parameter of the the "Set-NcSnapMirror" cmdlet.
SYNTAX Set-NcSnapmirror [-DestinationCluster <String>] -DestinationVserver <String> -DestinationVolume <String> [-SourceCluster <String>] [-SourceVserver <String>] [-SourceVolume <String>] [-Schedule <String>] [-Tries <Int32>] [-MaxTransferRate <Int64>] [-Policy <String>] [-Controller <NcController[]>] [-ZapiRetryCount <Int32>] [<CommonParameters>] -MaxTransferRate <Int64> Specifies the upper bound, in bytes per second, at which data is transferred between clusters. The default is unlimited (0) which permits the SnapMirror relationship to fully utilize the available network bandwidth. This option does not affect load-sharing mirrors and other SnapMirror relationships confined to a single cluster.
This could be achieved either via script\scheduled task or a WFA workflow. One other point to consider would be to ensure you account for any timezone differences if you are transferring to a remote site in a geo-graphically disperse infrastructure to ensure you the snapmirror transfer schedule is modified at the appropriate business hours of the destination system.
Hope that gives you some ideas.
/Matt