Do you have 'Marketo Sales Insights' available and implemented in your Sugar CRM? Have not used Sugar CRM yet, so do not know first hand.
If yes, you can create 'Sales Available' Campaigns in Marketo to send alert to the sales rep after '1 week', '1 month' or '3 months' etc.
in CRM, in Marketo Sales Insights area, you can see a drop down for 'Actions'. The sales reps can select 'Add to marketo campaign' and pick appropriate marketo campaign to get alerted on.