Nicky Hilton is ''too busy'' to plan her wedding.

The 31-year-old fashion designer and heiress, who got engaged to British banker James Rothchild in July after three years of dating, admits she has no idea when they will walk down the aisle.

The '365 Style' author told MailOnline: ''I haven't planned a thing for my wedding. I've been too busy.

''I just got back from New York and as soon as I landed in LA my mom was there with all this wedding planning material. She had tear outs and inspiration boards and was ready to talk wedding planning. But I am not there yet, I have not made one plan so far.''

The 'Real Housewives Of Beverly Hills' guest star added: ''I haven't even picked a date or a wedding planner. I have been busy with my book. But I am excited for what lies ahead, and I am looking forward to putting it together.''

The former model hasn't picked out her wedding dress yet.

She said: ''I honestly don't know what type of dress I will wear. But I have seen some fun ideas for bridesmaid gowns, where the dresses are all the same design but different sherbet colours. I like that.''

The blonde beauty got engaged to James during a romantic trip to Lake Como in Italy, but she doesn't know where they will exchange vows.

She said: ''It's a little difficult because I am from Los Angeles and he is from London. So we will need to find a place that is good for both of us. It will be a lot of planning, but it will be fun.''

Nicky's older sister Paris Hilton is looking forward to helping her organise the festivities.

The 33-year-old DJ said: ''I have actually never helped anyone plan a wedding before. So this is all new to me.''

She added: ''I am so happy for them. I cried when I heard the news they were engaged. They are perfect for each other.''