As a newly separating parent, you have three concerns that must be balanced: making things as easy as possible for the children, establishing a collaborative post-marital relationship with your ex partner, and protecting your parenting rights.
A good rule of thumb is to not make any big decisions without consulting with your attorney. Make sure that you understand under what circumstances your temporary parenting arrangements during this transition time may become set in stone for the long-term. What you want to avoid is agreeing to an arrangement because your kids are begging you to, or your ex is pressuring you, only to find out later that you have created a precedent for a parenting arrangement that you do not believe is in the best interest of your children.
The second balancing act is between providing your children with consistency in their relationships and activities while being flexible enough to meet their changing needs as they adjust to the enormous upheaval in their lives. There will be times when it is more important that they go to that soccer game because they have a commitment to the team while other times it may be more important for an impromptu ice cream outing with Dad/Mom to reassure them that he/she still loves them and will be in their lives.
You must trust that you know your kids and can tell one situation from the other. You need to let them know that this may be a difficult time for them and they may have more complicated feelings than usual but, at the same time, you expect them to fulfill their obligations and function to the best of their ability. A third balancing act occurs between attending to your needs and being responsive to the needs of your children. In order for the children to have their needs met to have two parents in their lives, and as long as dad/mom is not abusive, the children will spend some time with him/her. Whatever your parenting arrangement during the marriage, it is likely that you will spend less time with your children following the separation.
There will be times when you want the children to be with you when the plan is for them to be with their dad/mom. Your job at these times is to accept this with grace and not signal to your children that you are suffering or that they should resist parenting time with Dad/Mom in order to please you, placate you, or take care of you. The time when your kids are with their father is your time to pamper yourself, attend to the messy business of divorce, or simply be. Once your children return, it will be time to start balancing all over again!