Hi,
HLE is needed at the 2nd appt (Signing of Lease of agreement). It should be normally 4 mths after ur 1st appt( selection of flat,pay option fee tat 1).
However, for my case,i applied for the HLE during my 1st appt. I selected in march then may they call me for 2nd appt le. veri random de. So my HLE was still valid. Btw, HLE is valid for 3mths only. I tink gt pple encounter issue whereby their HLE expire b4 their 2nd appt cm. Not sure hw they resolved their issue but I tink if ur pay remains the same n u dun lose ur job,i dun tink its much of a issue. The intent is juz to make sure u dun bite off more than u can chew in terms of financing. Clarify with HDB lor juz to be sure. Anw,u need to reapply HLE when get key tat time cos need to settle the remaining of the loan le. Hope this helps.