I had Nikah and I have paid my Maher, but the main wedding ceremony will not be for 10 months. My question is do I have to pay all the expenses of my wife during this long delay?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

A husband is obliged to bear the expenditure of his wife in reasonable limits in return for enjoying his wife.  The Prophet (Sallallahu Alaihi wa Sallam) said in his farewell Hajj: “Fear Allah concerning women! Verily you have taken them on the Security of Allah, and intercourse with them has been made lawful unto you by Words of Allah. You too have right over them, and that they should not allow anyone to sit on your bed whom you do not like. But if they do that, you can chastise them but not severely. Their right upon you is that you should provide them with food and clothing in a fitting manner.” [Saheeh Muslim]

After having completed the marriage contract if the wife permits her husband to enjoy her then he is obliged to bear her expenditure whether he actually enjoys her or not. 

On the other hand, if the wife does not permit her husband to enjoy her or she permits him to enjoy her with limits not freely such as permitting him to enjoy in certain times or limited places or in certain ways; in this case he is not obliged to spend on her.

Therefore, if consummating the marriage is delayed by the husband, not from the wife, he is responsible to bear the expenditure. If the delay was due to the wife then he is no longer responsible to spend on her.

Allah knows best.