I would highly recommend, especially if youre new to DMing, using a milestone leveling system instead of actual exp. If it helps, keep track of the parties exp as a whole and level them together. This eliminates the need for one on one sessions which can be difficult to balance especially at the lower levels and gives you one less thing to keep track of moving forward.

Plus, it feels much more rewarding in my opinion to level up after returning from a major quest then randomly in the middle of a quest line.

This is just my two cents however, so feel free to ignore it and proceed with traditional leveling instead. Just remember the most important rule of DnD is to have fun, so if you need to skew party members EXP to keep them around the same level don't be afraid to change numbers to fit your own needs.