New Citizens Rights campaign from Home Office says “settled status” application form won’t go live till “late 2018” eucitizensrights.campaign.gov.uk
... which is a later range than “second half of 2018” used by ministers last year.. Then two years to do 3.5 million registrations... which is 6,731 per working day over 520 working days...
... so call that just under thousand applications per hour - or a registration system capable of granting an application every 3.75 seconds to get through all 3.5 million in two years
Home Office will be increasing staff in Visas & Immigration by 15% (1200) to deal with this, though as @YvetteCooperMP pointed out here ... it is probably an increase of 50% on workload 
NB - I presume someone already has won the contract to create the IT system? - there’s mention here of using driving licences as the model...
