Just keep shooting it until it's second nature
When I first got my g27, I took to the range a few times a week in the first few weeks and probably shot over 700-1000 rounds through it in a short amount of time! And in that time I did NOT shoot any other guns, period. I got very used to it fast and even after switching guns now, it's still feels like "home" to me.
When I hit the range now... I shoot off whatever my carry ammo is in the mag in the 27... then a few other mags in it... then I'll shoot whatever other guns I brought, but always before I leave I run a few more mags through the 27 just so it's the last one I shoot, always.
I do the above for any gun I carry, If i switch to something later, i'll do the same to it. I make sure that I am more comfortable and more proficient with my carry gun than any other gun I own. I also dry fired it daily at least 50 to 100 times for the first few weeks I had it as well, but that was mainly b/c I was new to glocks then and wanted to get the trigger learned(if that makes sense)...
Just keep shooting it and you will get better at switching back and forth.
Practice, Practice, Practice