Из всего этого задания интересует только один вопрос. Прошу ответить людей, действительно...

Из всего этого задания интересует только один вопрос.
Прошу ответить людей, действительно разбирающихся в английском языке.
Пропуск со словом START.
На сайте Гущина правильный ответ "will start", с чем я согласна в принципе, но меня волнует, подойдет ли здесь и настоящее совершенное "have started"?
Это задание было сегодня на экзамене по ОГЭ, и я написала "have started".
Как считаете вы и почему?


When you look at this lovely house in the Welsh countryside, you may think it's a picture from J.R.R. Tolkien's book "The Hobbit". In fact it's a real house designed by a real person. When ________THEY__________ first son was born, Simon Dale’s wife, Jasmine, said:
“I wish we _________LIVE_________ in the country. It would be so good for the baby”.
However, they ________NOT/HAVE__________ enough money to buy or rent a house in the country so they decided to take matters into their own hands. The house _________BUILD_________ by Simon himself, with a bit of help from his friends. The result was impressive. The home is made of natural materials, such as wood, stone and mud. It uses solar panels for energy and its water _________COME_________ from a nearby spring. It took Simon four months to complete his fairytale home. He managed to create a modern wooden eco-home – one of the _________WONDERFUL_________ houses you can imagine.
Simon Dale said, “I ________START__________ working on a new house of the same eco-style. My _________TWO_________ house will be smarter than the first one. My son _________BE_________ five now and I hope to celebrate his tenth birthday in a new house.”

When their first son was born, Simon Dale’s wife, Jasmine, said: “I wish we lived  in the country. It would be so good for the baby”.However, they didn't have enough money to buy or rent a house in the country so they decided to take matters into their own hands.The house was built by Simon himself, with a bit of help from his friends. The result was impressive. The home is made from natural materials, such as wood, stone and mud. It uses solar panels for energy and its water comes from a nearby spring. It took Simon four months to complete his fairytale home. He managed to create a modern wooden eco-home – one of the most wonderful houses you can imagine. Simon Dale said, “I have started working on a new house of the same eco-style. My second house will be smarter than the first one. My son is  five now and I hope to celebrate his tenth birthday in a new house