Hello! Yes, it is true that April and even early May is a bit early for most trekking, however there are a few places you can consider:
You can do the Ak-Sai glacier hike in Ala-Archa National Park. It's about a 12km hike to Ratzek Hut, at an altitude of around 3,300m. In April you will expect cold temperatures and snow, you'll need crampons and warm hiking gear.
Also in April there is some good hiking around the Chon-Kemin valley. You can hike to Karool-Dobo (Watch Hill) and Orto-Kaindi Gorge.
In May conditions will be better and there are more options.
There are good day hikes around Kol Tor Lake. And there's a three-day hike from Shamshy Gorge to Kol Tor Lake via Kegety Gorge.
From mid-May you can trek for three days at Son-Kul Lake, staying overnight in yurt camps, and also around Issyk-Kul lake.
