Just sharing my experience here.
Signed HDB agreement early April, agreed to give seller 3 month extension.
Had a contractor introduced to me by my landlord (currently staying in a rental master bedroom).
Brought this contractor for viewing and some measurements, but took 2 weeks to give quote based on what we wanted, and kept missing dates of when he would provide quote. Since we saw that the timing was coming close, I went on Hometrust and Qanvast to search for top 5 IDs and went to have meetings with 3 of them.
After comparisons and multiple meetings to align the scope of the works and bringing down the costs, we brought the final quote from about 38k down to 33k. During this process I created an excel sheet to compare the costs for the individual items, and eventually the cost difference amongst the 3 IDs came down to about $500. My wife and I went for the ID we had the best chemistry with.
Renovation started last Monday, and so far so good. The ID provided a project schedule and follow-up with photos and videos everyday about the progress.
Will update further.