This may help kick you along the right path, but if you are dealing with a large dataset this won't be good for performance...
declare @ID int; -- the first order number
set @ID=9;
select x.[OrderID], x.[Start], x.[End], y.[OrderID] as NextOrderId
from [Order] AS O
join [Schedule] AS S
on S.orderid = O.id
outer apply (
-- Find all scheduled orders that start on/after the selected order's start time
select *
from schedule AS sc
where sc.[Start]>= S.[Start]
and sc.[Start]<dateadd(day,datediff(day,0,S.[Start])+1,0)
) x
outer apply (
-- Find the next order in the schedule (SQL 2012 would make this easier)
select top 1 OrderID
from schedule AS sn
where sn.[Start]> x.[Start]
and sn.[Start]<dateadd(day,datediff(day,0,x.[Start])+1,0)
order by sn.[Start]
) y
where O.ID=@ID
order by x.[Start];
Results:
MM
select geometry::STGeomFromWKB(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