My fiancee is a PR and has a condo studio apartment along Aljunied road (partly financed by her father). Applying a resale/BTO will require a 30 mth wait from selling that. Should we sell/wait?

Ouch, this is tough.

30 months is a really long time. If it's a BTO you're after, do account for construction time as well; make sure you have a place to stay / have the funds for the temporary accomodation.

Is there a specific reason you're looking for a flat instead of other options? Give us a shout on Stacked Homes and we may be able to cast around for some alternatives for you.​​​

What do you mean by sell or wait? In order to buy a resale or HDB, you will have you first sell the condo and wait 30 months before doing so. So for now if you are only looking for BTO or resale, you have to sell the condo regardless. Resale might be more suitable in your case as a BTO will take a long time to be built.