Remember you are committing yourself to a resort that will not be fully operational for at least 6 months.
It will not be rentable for at least this period, and if you choose to live there it will be like living in a ghost town.
Also consider, the Spanish property market is in decline, There is a glut of unsold properties and developers are desperate to sell to alleviate cash flow problems. On this basis developers are offering various inducements to purchasers.
Remember the developer wants you to complete, he wants your money and he does not want you to forfeit your deposit. If he had a queue of new buyers then his attitude would be different, but this is not the case.
On this basis ask the developer what inducements he is prepared to offer you to complete.
Don't forget this is now a buyers market and that you are in control.