Boris is enjoying a bounce in the polls, they are calling it the Boris Bounce. It's the novelty factor, new hope, tough talk, bold promises. It's all vapour-wear, he's done nothing that you can see, feel or touch, but it is having a positive effect. This can only last for a very very short time because he stands no chance of delivering anything he has promised with such a weak majority. People will start to realise this extremely quickly and the Boris bounce will disappear as fast as it arrived. The votes will then flow back to BXP.
If he pounces on an election now, he might just win it with a workable majority. It's his only chance of clinging on for a full term. If he leaves it until October, he's had it.
Look at the way he is behaving, touring the country, pledging new train lines, promising more constables. This is a man in the middle of an election campaign, but Corbyn hasn't cottoned on yet and will be caught with his trousers down.
Just my observations.