HDB BTO as undergraduate + gf working full time need some advice regarding the process

Background info : Will be trying apply for BTO in 2022. At that point I will be just starting out my university at SMU (3.5 years). Expected to end in 2026. GF currently working full time as a dip holder earning roughly 1.7k before CPF will be working for at least 1 year by 2022.

Will be aiming for a non mature estate 4 room BTO which will be priced around 300k-320k based on previous estimates.

1) I understand that we will not be able to qualify for the deferred income assessment as my gf will be more than a year graduated from poly and will be working for at least 1 year in her job. As a result, the current HDB loan we are able to secure is 110k based on her sole income. With 75k in EHG. Will the loan amount increase & EHG change nearer to key collection as I would be working fulltime already due to a reassessment of income?

2) We would be able to qualify for the staggered payment scheme which works out to roughly 20k for the first 5% down payment including all the stamp duties & option fees. Could this amount be paid via the EHG ? (We have a combined total of about 20k in savings excluding emergency fund)