Allen has been impressive for Swans this season.
He said: "The experience of playing in the Premier League with Swansea has helped me massively, even though it's only a few appearances so far.
"When you come away with Wales, you know that international football is obviously a similar standard, so it gives you confidence you can handle it. There are so many good players in the Welsh squad that it would be hard not to enjoy it.
"Everybody wants to get the ball down and play and we did that on Friday night and hopefully can do the same thing in Bulgaria. We had nine Premier League players in the starting line-up and that shows you the strength that is developing in the squad.
"It is something that Wales have always needed. There are players coming through and getting better and gaining more experience and the performances are improving as a result. Quite a few of us have been together since the Under-21s and that definitely helps us because we know each other inside out.
"It's early days for me because it is only my fourth cap and my first start.
"So nothing changes from my point of view, in that I know I have to keep working hard every day in training and see what happens from there."