Johnson scored first as Spurs won 3-0 on the night.
He later said: "The last time I scored four in four was probably back in grassroots football. I had never done it before in professional football so it is a nice moment. To score and to win today when it was a real special performance from us it is a really good feeling.
"At first I wasn't sure if he (Micky van de Ven) was going to turn out and pass the ball back and keep possession, but once I saw him keep going, we all know how fast he is, not many people are going to stop him. When he got to the byeline and was looking to pass it I knew I just had to be there and I was happy to just tap it in."
On smiling before the ball had hit his boot, he added: "I was told by a few people that was the case. I think I just knew that I was alone and if the ball was right then it was going to be a goal."
On starting games fast, Johnson continued: "Yes that is what we do, it is what the manager talks about all the time. We are not a team that takes 10-15 minutes to get into a game because that's not the way we play. From minute one we have to be at the opponent so that they know they are in a game and it just brings out the best in us.
"If we can get a game with good intensity it suits us so much, and if we can score early on then even better, because it means teams have to open up a bit.
"It is a sign of intent from us. I think whatever competition it is important to get the wins. We came here with a clear game plan but at the end of the day we had to win. We can play as well as we can but if we don't come away with the win then it's all for nothing - we have learned that a few times this season so to win and get a clean sheet, it's a great day."