This code does not filter by folder path, so if you have more than one report on the server with the same report name, one report will be chosen arbitrarily and only one subscription will be executed.

declare
@report_name as varchar(100) = ‘My Report Name’
,@my_job_name as uniqueidentifier

–get job (subscription) GUID
SELECT top 1 @my_job_name = Schedule.ScheduleID
FROM ReportServer.dbo.Subscriptions
INNER JOIN ReportServer.dbo.ReportSchedule
ON ReportSchedule.SubscriptionID = Subscriptions.SubscriptionID
INNER JOIN ReportServer.dbo.Schedule
ON ReportSchedule.ScheduleID = Schedule.ScheduleID
INNER JOIN ReportServer.dbo.[Catalog]
ON ReportSchedule.ReportID = [Catalog].ItemID
AND Subscriptions.Report_OID = [Catalog].ItemID
WHERE
[Catalog].Name = @report_name

–email subscription report
EXEC msdb.dbo.sp_start_job @job_name = @my_job_name